八年级下册英语Unit3SectionB知识精讲(可编辑修改word版)
Unit 3 Section B 3a-Self Check 22-23人教版英语八年级下册(1)
Unit3 Could you please clean your room?
Section B (3a-Self Check)
学习目标
1、 复习巩固所学的词汇和短语。 2、 练习运用Could you please...?0Could I...?,并进行比较。 3、 会写表达自己观点的信件。
Revision— Translation competition翻译
典题训练
I.用括号内单词的适当形式填空 1. Many countries are making rules in order to fight (fight) pollution. 2. —It's our duty to keep (keep) our city clean and beautiful.
(A )15.一Could I watch TV this afternoon?
—Yes, you can. But first you ______fold your clothes.
A. have to C. may
B. can D. could
完成句子 16.他犯了个大错误,结果丢了工作。
He made one big mistake, and as a result , he lost his job.
③写作指导 ③写作指导 人称:第一人称。 时态:一般现在时为主。 结构设计: (1)在文章的第一段,提出自己对本单元写作的观点,即赞成还是反对孩子做 家务。 (2) 在文章的正文部分,对所提出的问题进行事实论证。 (3) 在文章结尾部分,总结归纳自己的观点。
八年级下册英语Unit3SectionB重要考点
Unit3 Could you please cleanyour room ?SectionB 重要知识点解说1.Could I invite my friends to a party ? 我能邀请我的朋友们来聚会吗?【分析】 invite sb. to Sp. 邀请某人去某地【分析】 invite v→ invitation n 邀请(1) invite sb. to do sth邀请某人做某事(2)invite sb. to + 地址邀请某人去某地You should refuse his __________(invite) .He is really friendly.He invited a lot of friends _________(come) to his birthday party.【2019 江西中考 4】 Lucy is shy. She would not invite her classmates ____ dancing with here.A. practiceB. practiceC. practingD. to practce2. No, you can ’havet a party. 不,你不可以举办聚会。
【分析】 can ’不t能;不会【2019 重庆 1】30. Hurry up , or you ____catch the train .A . can ’ tB . needn ’ t C. mustn't D. shouldn’t【2019 湖北黄冈】 37. — Who’ s the man over there? Is it Mr. Black?— It ______ be him. He’ s much taller.A. may notB. can’ tC. will notD. mustn’t3.I don ’ t understand why some parentsmake their kids help with housework and chores at home.我不理解为何有些父亲母亲在家让孩子们帮忙做家务和琐务。
2020-2021学年人教版八年级下册Unit3SectionB(2a-2b)教案
2.增加词汇练习环节,让学生在实际语境中运用词汇,巩固记忆。
3.培养学生的独立思考能力,鼓励他们在课堂上提出自己的观点。
4.加强放松训练,提高学生的自信心,帮助他们克服紧张情绪。
5.加大语法练习力度,让学生在反复实践中掌握语法知识。
2020-2021学年人教版八年级下册Unit3Section B (2a-2b)教案
一、教学内容
本节课为人教版八年级下册Unit 3 Section B (2a-2b)的内容。主要教学内容包括:2a部分对话练习,让学生通过角色扮演,运用一般将来时讨论未来的计划;2b部分阅读练习,学生阅读两篇关于未来梦想的小短文,理解文章大意并学会从文中提取关键信息。此外,还包括对本课重点词汇(如pilot、engineer、astronaut等)和语法(一般将来时)的讲解与练习,以及针对阅读策略的指导。通过本节课的学习,使学生能够自信地表达自己的梦想和未来计划,激发他们对未来的憧憬与期待。
五、教学反思
今天的教学活动让我对学生的学习情况有了更深入的了解。在教授Unit 3 Section B (2a-2b)时,我发现学生们对于一般将来时的掌握程度参差不齐,有的学生能够迅速理解并运用,而有的学生则在构造句子时感到困惑。这让我意识到,在接下来的教学中,我需要更加关注学生的个体差异,针对性地进行辅导。
(二)新课讲授(用时10分钟)
1.理论介绍:首先,我们要了解一般将来时的基本概念。一般将来时是英语中表达未来计划的时态,它通过be going to +动词原形的形式来构成。它是非常重要的,因为它帮助我们描述和规划未来的事件。
2.案例分析:接下来,我们来看一个具体的案例。这个案例中的角色使用了一般将来时来谈论他们的梦想和计划,展示了这个语法在实际中的应用。
人教版英语八年级下册Unit3 SectionB 教材知识详解
Unit3 SectionB 教材知识详解1. .Could I invite my friends to a party?我能邀请我的朋友们来派对吗?invite用作及物动词,常用构造:invite sb. to some place邀请某人去某地;invite sb. to do sth.邀请某人去故某事。
invite相当于ask。
如:We should invite our teacher to join in our party.我们应该邀请我们的教师参加聚会。
2.Kids these days already have enough stress from school.如今,孩子们已经承受了来自学校的足够多的精神压力。
enough stress足够多的精神压力。
stress为不可数名词,意为“精神压力;心理负担。
〞enough作形容词,修饰名词时,可放在名词的前面,也可以放在名词的后面,习惯放在名词的前面。
enough作副词时,要放在形容词/副词后,即后置。
如:We have enough money to buy a car.我们有足够的钱买一辆车。
3. Housework is a waste of their time.做家务是在浪费他们的时间。
a waste of为固定短语,意为“浪费〞,waste在这里作名词。
如:That’s a waste of money.那太浪费钱了。
4. They should spend their time on schoolwork in order to get good grades and get into to a good university.为了取得好成绩,进入一所好大学,他们应该把时间花在学业上。
spend花费,其主语必须是表示人的名词或代词,常用于spend some time/money on sth或spend some time/money doing sth.构造中,其中的介词in可以省去。
八下unit3 SectionB 3a_Self Check -八年级下册英语同步课件(人教版)
A. will finish
B. finish C. have finished
4. Some teenagers spend their free time______volunteer work.
A. on
B. in
C. with
5. The ball______me fifty dollars and I have to______5
3a Do you think children should do some chores at home? Why or why not? Discuss this with a partner and take notes.
Children should do Children should not do
For example, they should make their own beds and clean their own rooms because they are the ones who use these. They may not have time to help with the other parts of the house, but they should try to be responsible for their own areas. This will help them to grow up to be independent and responsible adults.
2021年初中英语人教新目标版八年级下册 Unit 3 Section B(1a-1e) 教案
Ⅱ.根据句意及首字母完成单词。
1. Thanks a lot for invitingus to your birthday party.
2. You can borrowmy bike, but you must give it back to me this afternoon, because I’ll have to use it then.
2. Play the tape for the first time to get the main idea.
3. Check the answers.
4. Play it again for them to complete the sentences in 1d.
5. Listen to the tape, then check the answers.
____7. take out the rubbish
____8. make your bed
1. Ss discuss the questions.
2. Ss answer the questions.
3. Ss finish 1a.
通过“做家务”这一话题导入新课。
教学环节
教师活动
学生活动
备课札记
2. Ss show their dialogues.
通过口语结对活动,置学生于语言环境交际之中,调动学生的参与热情,将课堂教学成为一个师生共同学习创造的过程。
Step 3
Listening
(1c&1d)
1. Get the students have a quick look at the instructions of these two activities, so they can know how to do them.
人教新目标版八年级英语下册Unit3SectionB(2a-2e)课件
I don’t understand why some parents make their kids help with housework and chores at
Topic sentence
home. Kids these days already have enough
stress from school. They don’t have time to
Example
often fell ill and his grades dropped. The earlier kids
learn to be independent, the better it is for their future.
Mr. Smith
Conclusion
Mr. Smith thinks kids _sh_o_u_l_d_do chores.
Reasons
after themselves. It also helps them to understand the
idea of fairness. Since they live in one house with their
parents, they should know that everyone should do
these days depend on their parents too much. They’re
always asking, “Could you get this for me?” or “Could
you help me with that?” Doing chores helps to develop children’s independence and teaches them how to look
Unit 3 Section B (2a-2e) 22-23人教版八年级英语下册
Skimming 意为“快速掠过,从中提取最容易取得的精华”。 这种读法包含有原词的所有意思——快速读过去,取出读物 中关键性的东西。因此,我们可以把这种读法理解为快速浏览 课文,领会文章大意。一般而言,通过标题可知道文章的主题。 对文章的首段和末段要多加注意,以便发现作者的观点。
Ms. Miller (cons)
The Sunday Mail magazine
Dear Sir, I don’t understand why some parents make their kids help with housework and chores at home. Kids these days already have enough stress from school. They don’t have time to study and do housework, too. Housework is a waste of their time. Could we just let them do their job as students? They should spend their time on schoolwork in order to get good grades and get into a good university. Also, when they get older, they will have to do housework so there’s no need for them to do it now. It is the parents’ job to provide a clean and comfortable environment at home for their children. And anyway, I think doing chores is not so difficult. I don’t mind doing them. Ms. Miller
人教版英语八年级下册Unit3_Section B (2a~2e)教案与反思
Section B第4课时(2a~2e)新竹高于旧竹枝,全凭老干为扶持。
出自郑燮的《新竹》前进学校史爱东类别学习重点重点单词stress, waste, provide, anyway, depend, develop, fairness, since, neighbor,ill, drop重点短语in order to, depend on, take care of, provide sth. for sb., as a result, doone’s part in, do not mind doing sth.重点句式1.They should spend their time on school work in order to get good grades.2.There is no need for them to do it now.3.The earlier kids learn to be independent, the better it is for their future.课前预习写一写1.压力stress2.浪费;垃圾waste3.提供;供应provide4.而且;加之anyway5.依靠;依赖depend6.发展develop7.公正性fairness 8.因为;既然 since9.邻居neighbor 10.有病;不舒服ill 11.落下;掉下drop译一译1.为了in order to2.依靠depend on3.照顾take care of4.为某人提供某物provide sth. for sb.5.结果as a result6.在……上尽一份力do one’s part in7.不介意做某事do not mind doing sth.背一背1.为了取得好成绩他们应该花时间在学习上。
They should spend their time on school work in order to get good grades.2.我认为做家务没那么难。
新人教版八年级下册Unit3SectionB2b知识点
段落结构合理
段落的结构应符合逻辑, 段落中的句子应按照逻辑 顺序排列,使读者能够顺 畅地理解文章内容。
段落间过渡自然
段落间的过渡要自然流畅 ,可以使用过渡词或短语 来连接不同段落,使文章 整体连贯。
句子结构
简单句与复合句结合
在写作中,应将简单句与复合句结合使用,以提高文章的表现力 和层次感。
长句与短句搭配
示例
I have already finished my homework. (我已经完成了作业。)
现在完成进行时态
总结词
示例
表示过去开始的动作一直持续到现在 ,并可能继续下去
I have been studying English for three years. (我学英语已经三年了。)
详细描述
题目2
Complete the following paragraph with the missing words: I went to the _____ yesterday and had a great time.
题目3
In the story, the hero ____ a magic sword and used it to defeat the dragon.
现在完成进行时态由助动词 have/has+been+动词的现在分词构成,强 调动作的持续性。常与for引导的时间状语连 用,表示动作从过去某个时间开始一直持续 到现在。
过去完成时态
总结词
表示过去的过去发生的动作
详细描述
过去完成时态由助动词had+过去分词构成,表示在过去的某个时间之前已经完成的动作 。常与before, by等连词引导的时间状语连用。
英语人教版八年级下册Unit3 Section B(2b--2e)
Careful reading Read letter one, finish the following tasks.
Task 1
Circle “T” or “F”
Reading strategy(阅读策略)
( F)1. Miller thinks kids these days have less stress from
The structure of
(结构)
Letter One
shouldn’t
Opinion
spend in order to
Parents’ provide clean comfortable
Reasons
waste no need students
support(支持) the reasons Conclusion (结论)
and comfortable environment at home for their
children.-
Careful reading Read letter two and finish the following tasks.
任务一 完成句子
1. Mr. Smith thinks these days children depend on their parents too much _______________________.
Unit 3知识点精析(下)+课文注释人教版英语八年级下册
人教版丨初中英语八年级下册Unit 3知识点精析(下)+课文注释1.invite my friends to a party邀请我的朋友们来参加聚会要点精析invite为及物动词,意为“邀请”。
invite sb.to do sth.意为“邀请某人做某事”。
例:We invited all our friends.我们邀请了我们所有的朋友。
Kate invited me to go to the movies with her.凯特邀请我和她一起去看电影。
知识拓展invite 的名词形式为invitation,意为“邀请;请帖”。
例:Thank you for your kind invitation.谢谢你的盛情邀请。
2. I do not understand why some parents make their kids help with housework and chores at home.我不理解为什么一些父母让他们的孩子在家帮忙做家务。
要点精析make their kids help with housework and chores 是 make sb. do sth.结构,此结构意为“让/使某人做某事”。
例:This good news made her laugh happily.这个好消息使她开心地笑了。
3.Housework is a waste of their time.(做)家务是浪费他们的时间。
要点精析a waste of...意为“浪费……”,其中waste是名词,意为“浪费;滥用”。
例:Playing computer games is a waste of time.玩电脑游戏是浪费时间的。
知识拓展waste还可作动词,意为“浪费”。
例:Don't waste your money on clothes.别把你的钱浪费在衣服上。
4. They should spend their time on schoolwork in order to get good grades and get into a good university.为了取得好成绩,进入一所好大学,他们应该把他们的时间花在学业上。
人教八年级英语下册 Unit3 SectionB 重点知识归纳及练习
Unit3 SectionB 重点知识归纳及练习11.buy some drinks and snacks买一些饮料和小吃(1)buy-bought- bought 动词,意为“购买;买”。
buy sb.sth.= buy sth. for sb.意为“给某人买某物”。
eg: Yesterday my father bought me an English dictionary.=Yesterday my father bought an English dictionaryfor me.昨天爸爸给我买了本英语词典。
(2) snack可数名词,意为“点心;小吃;快餐”。
Drinks and snacks are served at the bar.酒吧里供应饮料和小吃。
2invite my friends to a party邀请我的朋友们来参加聚会invite及物动词,意为“邀请”。
名词形式为invitaion,意为“邀请;请柬”。
其常见的用法有:①“invite sb.to+地点名词”意为“邀请某人到某地”。
I invited Jenny to my house.我邀请珍妮到我家。
②invite sb. to do sth.意为“邀请某人做某事”。
They invite me to play the game.他们邀请我来玩这个游戏。
>>>>P教材223I do not understand why some parents maketheir kids help with housework and chores at home.我不理解为什么一些家长社他们的孩子在家里帮着做家务。
(1) make sb. do sth.意为“让/使某人做某事”。
为不带to的动词不定式(短语)作宾语补足语。
常见的类似用法还有:let/ have sb do sth.eg: He made me wait there for two hours.他让我在那里等了两个小时。
2020年春人教新目标英语八年级下册Unit3-重点知识点讲解(无答案)
2020年春人教新目标英语八年级下册Unit3 Could you please clean your room?单元知识点总结讲解Section A1.Peter ,could you please take out the trash? 彼得,你能把垃圾倒了吗?Could you please do sth ?请你(做)......好吗?用于提出请求,希望得到对方的肯定回答,说话的语气比较客气委婉。
Could 不是can的过去式,是委婉、礼貌的说法。
【常用答语】肯定回答:Sure./ Of course./ Certainly./No problem.否定回答:Sorry , I can’t( )1..—Could I borrow your camera?— ___________,but please give it back by Saturday.A. I am sorryB. Of courseC. Certainly notD. No, thanks( )2.—Sir , could you please put out your cigarette? This is asmoke-free(无烟的)school.— __________A. I'm sorry about this.B. No problemC. Sure, I'd love toD. Never mind2. Can you do the dishes.?那你可以洗盘子吗?do the dishes 洗碗【结构1】do the +名词:do the dishes/ laundry 洗餐具/衣服【结构2】do the +动词-ing do the cleaning 打扫卫生【结构3】do one’s + 名词do one’s housework/ homework 做家务/家庭作业【结构4】do some +动词-ing do some reading/ shopping 读写书/购物①His mother ______________________(洗碟子) in a restaurant.3.Could I at least finish watching this show? 至少让我看完这个节目可以吗?1)Could I do a sth? 我可以做......吗?用于表达请求,语气比较委婉。
新目标人教版初中英语八年级下册Unit3_SectionB_语境法讲解单词
比较 一人一双(pair)很公平(fair)。
unfair [ʌn'feə, ʌn'fer] adj. 不合理的; 不公正的
we take and the things that happen to us.
③Drop everything and come at once!
停止
熟词生义
写
④Drop me a line when you get there.
送
⑤He believes that dropping people in their homes safely is the best reward
词块搭配
(3) __________d_ro_p__b_y_/_in_________顺便走访 (4) _______d_r_o_p__o_u_t_o_f_s_c_h_o_o_l____辍学
练练不忘
( 1 ) My grandmother took out a fifty-yuan note ( 纸 币 ) and _d_r_o_p_p__ed___(drop)it on the ground. (2)(2018本溪改编)—Uncle Wang,I _d_r_o_p_p_e_d__b_y(顺便走访) your home at 6:00 p. m. yesterday, but nobody was in. —Oh, I was having a meeting. (3)Steve had played online games since the age of eleven. He almost __d_r_o_p_p_e_d_o_u_t__fr_o_m__s_c_h_o_o_l__(辍学)last year.
2020春鲁教版(五四学制)英语八年级下册:Unit3-Section B(2a-Self Check)
4.坚持你的梦想,永不放弃!
Hold
on
to your dreams and never give up!
5.他们愿意为了梦想而努力。
They are
willing
to work hard for their dreams.
三、短文填空(课文改编) 用方框中所给单词或短语填空。(有两个多余)
fly,according to,conclusion,offer,realistic,continue,across, hold out,findings,as soon as possible,provide,hold on
—We are A about how teenagers spend their free time.
A.doing a survey
B.making a card
C.searching
D.studying
5.—What would you like to do when you finish school?
Unit3 人教部编版八年级英语下册SectionB大课文第2段笔记
1.depend on sb/sth(依靠某人/某物)dependent (adj依靠的,依赖的) →dependence (n依靠,信赖) in dependent (adj独立的,自主的) →in dependence ( n独立)2. They are always askingbe always doing sth注(不是进行时态,是一个固定结构,常用来表示“总是做某事”)3.develop v. 发展,壮大V.培养,养成develop one’s independence培养独立性development n. 发展with the development of…随着…的发展例:With the development of the online shopping, our life becomes more and more convenient.随着网上购物的发展,我们的生活变得越来越方便。
developed adj. 发达的 a developed country一个发达国家developing adj. 发展中的a developing country一个发展中国家4. fair ness n. 公平,公正(不可数)fair adj. 公平的,公正的,合理的un fair adj. 不公平的,不公正的,不合理的It + is + fair/unfair (for sb.) to do sth.(对某人来说) 做某事是公平/不公平的例:It is fair for him to get the first place, because he works hard all the time.对他来说得到第一名是合理的,因为他总是努力学习。
5.do one’s part (in doing sth)尽某人的职责(做某事)例They do their part in cleaning their room.6. take care of (照顾,处理)take care of=look after=care for, 其后接名词,代词。
- 1、下载文档前请自行甄别文档内容的完整性,平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益,请联系客服反馈,我们会尽快为您处理(人工客服工作时间:9:00-18:30)。
Unit3 SectionB 重难点讲解与练1.Could I invite my friends to a party?我能邀请我的朋友们来聚会吗?【解析】invite sb. to Sp. 邀请某人去某地【解析】invite v → invitation n 邀请(1)invite sb. to do sth 邀请某人做某事(2)invite sb. to +地点邀请某人去某地You should refuse his (invite) .He is really friendly.He invited a lot of friends (come) to his birthday party.【2013 江西中考4】Lucy is shy. She would not invite her classmates dancing with here.A. practiceB. practiceC. practingD. to practce2.No, you can’t have a party. 不,你不能举办聚会。
【解析】can’t 不能;不会【2013 重庆1】30.Hurry up,or you catch the train.A.can’t B.needn’t C.mustn't D. shouldn’t【2013 湖北黄冈】37. —Who’s the man over there? Is it Mr. Black?—It be him. He’s much taller.A. may notB. can’tC. will notD. mustn’t3.I don’t understand why some parents make their kids help with housework and chores at home.我不理解为什么有些父母在家让孩子们帮忙做家务和杂务。
【解析】make sb. do sth 让某人做某事make → made →made v. 做,制作,使得(1)make sb/sth + 形容词“让某人或某物…”make you happy(2) make sb/sth do sth 使某人做某事make me laugh.( ) Colors can change our moods and make us happy or sad, energetic or sleep.A. to feelB. feelingC. feltD. feel【2013湖北鄂州】28. —I’m very tired these days because of the senior high school entrance examination(中考).—Why not music? It can make you .A. listen to; relaxedB. to listen to; relaxedC. listen to; relaxD. to listen to; to relax【2013 重庆中考】He lost his key. It made him in the cold to wait for his wife’s return.A. to stayB. stayedC. staysD. stay【make 短语】:make sure 确信make a dialogue 编对话make a mistake 犯错误(by mistake 由于疏忽)make a noise 吵闹make faces 做鬼脸make friends (with)和..交朋友make room for 给..让地方make tea 沏茶make money 赚钱make a decision 作出决定make the bed 整理床铺make a living 谋生make fun of = laugh at 取笑【2012 曲靖中考】Every morning I (整理床铺) and clean the living room.4.They don’t have time to study and do housework,too.他们也没有时间来学习家务和做家务。
【解析】have time to do sth.有时间做某事have time =be free 有空5.Housework is a waste of their time. 做家务是在浪费他们的时间。
【解析】a waste of 浪费 a waste of time 浪费时间 a waste of money 浪费金钱( ) Don’t water. Can’t you see the sign “save water”?(waste)6.They should spend their time on schoolwork in order to get good grades and get into a good university.为了取得好成绩并考上一所好大学,他们应该把时间用在学习上。
【解析1】spend... on sth 在某事上花费......spend/pay/cost/take 花费(1)s pend→spent→spent v 花费,主语是人◆sb.+ spend +时间/钱+on sth ◆sb. +spend +时间/钱+(in)doing sth ◆spend on= pay for 支付He spends too much time on the computer games.( ) Remember to spend some time your loved ones, because they’re not going to be around forever.A. fromB. withC. inD. on( ) 【2012 湖南永州】My father one hundred thousand yuan on his new car.A. spentB. costC. paid (2)pay →paid →paid v支付,主语是人◆sb.+ pay + 钱+for sth I pay 10 yuan for the book.( ) — How much did you for this computer?— Five hundred dollars.A. costB. takeC. spendD. pay(3)cost→ cost→ cost v 花费,主语是某物或某事◆sth cost sb. +钱某物花费某人多少钱A new computer costs me a lot of money.( )【2012 广西贵港】I bought a new sweater last weekend. It me 120 yuan.A.paidB. takeC. costD. spend(4)take→took→ taken v 花费◆It takes /took sb. some time to do sth. 做某事花费某人多长时间It takes him 3 hours to do his homework.【2013 黑龙江绥化】10. It will them several years to learn English well.A.costB. takeC. spend【2012 曲靖中考】--Are you always online?--Yes. It me a lot of time to read the web pages I likes. It’s the best way to kill time.A. takesB. spendsC. usesD. pays【2013 鞍ft】It only him 20 minutes to his office every day.A. takes, to driveB. took, driveC. takes, driveD. took, to drive【2013 湖北荆州】22. It usually Mum about half an hour to cook supper.A. paysB. takesC. spendsD. costs【2013 四川雅安】4. I spent $5 this book.A. inB. to buyC. buyingD. buy【2013 ft东济宁】22. — Do you know the price of the ticket?—Yes. Each ¥180.A. paysB. costsC. takesD. spends【2013 四川遂宁】24. Paul’s parents were worried that he too much time chatting on line.A. spentB. paidC. took【2013 ft东青岛】9. — How much is the ticket to Central Park?—A one-way ticket $40, and you can another $20 for a round-trip.A. costs, payB. cost, spendC. pay, spendD. spends, pay【解析2】in order to “目的是;为了”后接动词原形。
in order to do sth 为了做某事( ) He ran quickly in order not late for the meeting. A. to be B.be C. being【2012 江苏连云港2】A lot of doctors gathered in Harbin save “China’s most beautiful teacher” — Ms. Zhang Lili.A. So thatB.in order toC.in order thatD.as a result【解析3】get into =enter 进入get up 起床get back 返回get over 克服【2013 新疆乌鲁木齐2】27. If Ted can his difficulties, he’ll make great progress.A. come overB. get overC. get offD. come out7.It is the parents’ job to provide a clean and comfortable environment at home for their children.在家为孩子们提供一个干净、舒适的环境是父母的义务。