充要条件PPT课件
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第4课时 充要条件
要点·疑点·考点 课 前 热 身 能力·思维·方法 延伸·拓展 误 解 分 析
要点·疑点·考点
1.若A=>B且B推不出A，则A是B的充分非必要条件 2.若A推不出B且B=>A，则A是B的必要非充分条件 3.若A=>B且B=>A，则A是B的充要条件 4.若A推不出B且B推不出A，则A既不是B的充分条件， 也不是B的必要条件.
had expected, was over 200.
Meaning: “as” means: 正如…一样
We won the game, which we hadn’t expected.
as
He is such a clever boy _a_s__ can solve all the questions.
返回
课前热身
1.已知p是q的必要而不充分条件，那么┐p是┐q的 ___
2.若A是B的必要而不充分条件，C是B的充要条件，D 是C的充分而不必要条件，那么D是A的________
3.关于x的不等式：｜x｜+｜x-1｜＞m的解集为R的 充要条件是( )
(A)m＜0 (D)m≤1 答案： (1)充分不必要条件 (2)充分不必要条件 (3)C
The lady who is getting off the bus is a musician.
正在走下汽车的那位女士是个音乐家。
The lady is a musician,who is getting off the bus.
那位女士是个音乐家,她正在走下汽车。
典型例题
Helen was much kinder to her
personally I doubt very much.
(1999)
A. it
B. that
C. when
D. which
典型例题
The factory produces half a million pairs of shoes every year, 80% ___A_____ are sold abroad. (2004, 辽宁卷)
Beijing,which is the capital of China, is a very beautiful city.
This is the dictionary which helps me a lot.
2 意义不同
一般情况下，限制性定语从句是用来限制先 行词的意思，与先行词关系紧密，如果去掉的 话会使句子意思不明确；而非限制性定语从句 与先行词关系松散，常对先行词起附加说明的 作用，即使去掉也不影响句子的主要意思。
A. of which B. which of C. of them D. of that
05年高考回放
1. I have many friends, _______ somDe are businessmen. (2005， 全国II卷)
A. why
B. from which
C. who of D. of whom
3. _A__s_ we hoped, he came to help us. 4. A__s_ was planned, the work was finished
on time.
5. The number of the visitors, _a_s__we had
expected, was over 200. “as” can be used to refer to a whole
c2=(a2+b2)r2
【解题回顾】对于涉及充分必要条件判断的问题 ，必须以准确、完整理解充分必要条件的概念为 基础.有些问题需转化为等价命题后才容易判断， 因此要理清充分必要条件与四种命题真假的关系.
2．求证：关于x的方程ax2+bx+c=0有一个根为-1的 充要条件是a-b+c=0.
【解题回顾】充要条件的证明一般分两步：证充分 性即证A =>B，证必要性即证B=>A一定要使题目与 证明中的叙述一致
3引导词不完全相同
非限制性定语从句有两个禁忌：that和why不 能引导非限制性定语从句。在非限制性定语 从句中，that的作用由who，whom和which分 别承担。
Yesterday I met jenny, who was very tired.
引导词的省略情况不同
在限制性定语从句中，关系代词充当宾语时 可以省略。
= and it
“which” can be used to refer to __t_he_w__h_o_le__ _s_en_t_e_n_ce__.
1. He is a hard working student, _a_s_ we all know.
2. He has won first prize, _a_s__ we all expected.
The old man has a son,who is a
doctor.
那老人有一个儿子，今年18岁。
（定语从句起补充说明作用；老人只有一个儿子。）
Compare:
Nanjing is a city _____t_h_a_t_/w_ hich
lies on the Changjiang River.
2．If a shop has chairs _______ woDmen can park their men, women will spend more time in the shop. (2005，上海卷)
2.搞清①A是B的充分条件与A是B的充分非必要条件 之间的区别与联系；②A是B的必要条件与A是B的必 则容易在这一点上出错误.
返回
U3 Grammar
Non-restrictive attributive clauses (1st period)
Who is she?
She is zhang Baizhi,w_ctive She is zhang Baizhi,_w_h_o_m we often talk about.
答案： (4) C
(5) A
返回
能力·思维·方法
1.在下列各题中，判断A是B的什么条件，并说明理由 (1)A：|p|≥2，p∈R,B:方程x2+px+p+3=0有实根； ( 2 ) A：α+β=2kπ，(k∈Z),B:sin(α+β)=sinα＋ sinβ; (3)A：√1+sinθ=a，B：sin(θ/2)+cos(θ/2)=a； (4)A：圆x2+y2=r2与直线ax+by+c=0相切，B：
返回
延伸·拓展
3．求关于x的方程ax2+2x+1=0至少有一个负的实根 的充要条件.
【解题回顾】本题解答时，一是容易漏掉讨论方程 二次项系数是否为零，二是只求必要条件忽略验证 充分条件.即以所求的必要条件代替充要条件.
返回
误解分析
1.在写某条件的充分或充要条件时，要特别注意的 是它们能否互相推出，切不可不加判断 以单向推出代替双向推出.
I live in Nanjing , _____w__h_i_ch
lies on the Changjiang River.
I live in Nanjing, _____w__h_e_r_e_/in which
you can find many places of interest.
Compare:
I lost the photos (that/which) I took in Iraq.
在非限制性定语从句中，关系代词无论在什么情况 下都不可以省略。
4 译法不同
翻译限制性定语从句时，通常是把从句翻译 成定语放在先行词前，也就是说，先翻译 定语从句，后翻译先行词。而翻译非限制 性定语从句时，从句不放在先行词前，按 顺序先译先行词，后译定语从句即可。
(B)m≤0
(C)m＜1
4.对于集合M，N和P，“P M且P 的( ) (A)充分而不必要条件 (B)必要而不充分条件 (C)充要条件 (D)既不充分也不必要条件
N”是“P
M∩N”
5.已知P：｜2x-3｜＞1；q：1/(x2+x-6)＞0，则┐p 是┐q的( ) (A)充分不必要条件 (B)必要不充分条件 (C)充要条件 (D)既不充分也不必要条件
Mr Smiths, whose wife teaches singing, is a teacher of piano.
Compare:
The old man has a son who/that
is a doctor.
那个老人有一个18岁的儿子。 •(定语从句起限定作用；老人还可能有其他儿子。 )
=for he
I will take this one, which seems to be the best one.
=for it
They gave us the design for free, which was a very good one.
=though it
Compare: He told me a story, which is already known to all. He came late, which made the teacher angry. He missed the movie, which was a great pity.
sentence.
What’s the difference between “which” and “as” when they refer to a whole sentence?
Structure:
As was expected, we won the game. We won the game, which/as we expected. The number of the visitors, as/which we
She is a girl __w_h_o_/_th_a_t is very slim and attractive. She is a girl ___(w_h_o_/t_h_at) we often talk about
I, who am your best friend, believe in you.
• Compare: •China has hundreds of islands,
the largest of which is Taiwan. I like the house of which the roof is blue.
the roof of which whose roof
I need this man, who can speak English.
This is such an interesting book _a_s__ interests all students.
This is so difficult a question _a_s__ no one can work out.
He is so popular a person _a_s_ we all like to talk with.
youngest son than to the others, _____, of Dcourse, made the others envy him. (2004, 天津卷)
A. who
B. that
C. what
D. which
2. Carol said the work would be done by October, __D___
He has three sons who/that are doctors.
He has three sons, two of whom are doctors.
He has three sons, all of whom are doctors.
He has three sons, none of whom are doctors.
I bought the same car _a_s_ he is driving.
What is the difference between the restrictive attributive clauses and the non-restrictive clauses?
1.形式不同
限制性定语从句和先行词之间不用逗号隔开； 非限制性定语从句与先行词之间要用逗号隔开。
要点·疑点·考点 课 前 热 身 能力·思维·方法 延伸·拓展 误 解 分 析
要点·疑点·考点
1.若A=>B且B推不出A，则A是B的充分非必要条件 2.若A推不出B且B=>A，则A是B的必要非充分条件 3.若A=>B且B=>A，则A是B的充要条件 4.若A推不出B且B推不出A，则A既不是B的充分条件， 也不是B的必要条件.
had expected, was over 200.
Meaning: “as” means: 正如…一样
We won the game, which we hadn’t expected.
as
He is such a clever boy _a_s__ can solve all the questions.
返回
课前热身
1.已知p是q的必要而不充分条件，那么┐p是┐q的 ___
2.若A是B的必要而不充分条件，C是B的充要条件，D 是C的充分而不必要条件，那么D是A的________
3.关于x的不等式：｜x｜+｜x-1｜＞m的解集为R的 充要条件是( )
(A)m＜0 (D)m≤1 答案： (1)充分不必要条件 (2)充分不必要条件 (3)C
The lady who is getting off the bus is a musician.
正在走下汽车的那位女士是个音乐家。
The lady is a musician,who is getting off the bus.
那位女士是个音乐家,她正在走下汽车。
典型例题
Helen was much kinder to her
personally I doubt very much.
(1999)
A. it
B. that
C. when
D. which
典型例题
The factory produces half a million pairs of shoes every year, 80% ___A_____ are sold abroad. (2004, 辽宁卷)
Beijing,which is the capital of China, is a very beautiful city.
This is the dictionary which helps me a lot.
2 意义不同
一般情况下，限制性定语从句是用来限制先 行词的意思，与先行词关系紧密，如果去掉的 话会使句子意思不明确；而非限制性定语从句 与先行词关系松散，常对先行词起附加说明的 作用，即使去掉也不影响句子的主要意思。
A. of which B. which of C. of them D. of that
05年高考回放
1. I have many friends, _______ somDe are businessmen. (2005， 全国II卷)
A. why
B. from which
C. who of D. of whom
3. _A__s_ we hoped, he came to help us. 4. A__s_ was planned, the work was finished
on time.
5. The number of the visitors, _a_s__we had
expected, was over 200. “as” can be used to refer to a whole
c2=(a2+b2)r2
【解题回顾】对于涉及充分必要条件判断的问题 ，必须以准确、完整理解充分必要条件的概念为 基础.有些问题需转化为等价命题后才容易判断， 因此要理清充分必要条件与四种命题真假的关系.
2．求证：关于x的方程ax2+bx+c=0有一个根为-1的 充要条件是a-b+c=0.
【解题回顾】充要条件的证明一般分两步：证充分 性即证A =>B，证必要性即证B=>A一定要使题目与 证明中的叙述一致
3引导词不完全相同
非限制性定语从句有两个禁忌：that和why不 能引导非限制性定语从句。在非限制性定语 从句中，that的作用由who，whom和which分 别承担。
Yesterday I met jenny, who was very tired.
引导词的省略情况不同
在限制性定语从句中，关系代词充当宾语时 可以省略。
= and it
“which” can be used to refer to __t_he_w__h_o_le__ _s_en_t_e_n_ce__.
1. He is a hard working student, _a_s_ we all know.
2. He has won first prize, _a_s__ we all expected.
The old man has a son,who is a
doctor.
那老人有一个儿子，今年18岁。
（定语从句起补充说明作用；老人只有一个儿子。）
Compare:
Nanjing is a city _____t_h_a_t_/w_ hich
lies on the Changjiang River.
2．If a shop has chairs _______ woDmen can park their men, women will spend more time in the shop. (2005，上海卷)
2.搞清①A是B的充分条件与A是B的充分非必要条件 之间的区别与联系；②A是B的必要条件与A是B的必 则容易在这一点上出错误.
返回
U3 Grammar
Non-restrictive attributive clauses (1st period)
Who is she?
She is zhang Baizhi,w_ctive She is zhang Baizhi,_w_h_o_m we often talk about.
答案： (4) C
(5) A
返回
能力·思维·方法
1.在下列各题中，判断A是B的什么条件，并说明理由 (1)A：|p|≥2，p∈R,B:方程x2+px+p+3=0有实根； ( 2 ) A：α+β=2kπ，(k∈Z),B:sin(α+β)=sinα＋ sinβ; (3)A：√1+sinθ=a，B：sin(θ/2)+cos(θ/2)=a； (4)A：圆x2+y2=r2与直线ax+by+c=0相切，B：
返回
延伸·拓展
3．求关于x的方程ax2+2x+1=0至少有一个负的实根 的充要条件.
【解题回顾】本题解答时，一是容易漏掉讨论方程 二次项系数是否为零，二是只求必要条件忽略验证 充分条件.即以所求的必要条件代替充要条件.
返回
误解分析
1.在写某条件的充分或充要条件时，要特别注意的 是它们能否互相推出，切不可不加判断 以单向推出代替双向推出.
I live in Nanjing , _____w__h_i_ch
lies on the Changjiang River.
I live in Nanjing, _____w__h_e_r_e_/in which
you can find many places of interest.
Compare:
I lost the photos (that/which) I took in Iraq.
在非限制性定语从句中，关系代词无论在什么情况 下都不可以省略。
4 译法不同
翻译限制性定语从句时，通常是把从句翻译 成定语放在先行词前，也就是说，先翻译 定语从句，后翻译先行词。而翻译非限制 性定语从句时，从句不放在先行词前，按 顺序先译先行词，后译定语从句即可。
(B)m≤0
(C)m＜1
4.对于集合M，N和P，“P M且P 的( ) (A)充分而不必要条件 (B)必要而不充分条件 (C)充要条件 (D)既不充分也不必要条件
N”是“P
M∩N”
5.已知P：｜2x-3｜＞1；q：1/(x2+x-6)＞0，则┐p 是┐q的( ) (A)充分不必要条件 (B)必要不充分条件 (C)充要条件 (D)既不充分也不必要条件
Mr Smiths, whose wife teaches singing, is a teacher of piano.
Compare:
The old man has a son who/that
is a doctor.
那个老人有一个18岁的儿子。 •(定语从句起限定作用；老人还可能有其他儿子。 )
=for he
I will take this one, which seems to be the best one.
=for it
They gave us the design for free, which was a very good one.
=though it
Compare: He told me a story, which is already known to all. He came late, which made the teacher angry. He missed the movie, which was a great pity.
sentence.
What’s the difference between “which” and “as” when they refer to a whole sentence?
Structure:
As was expected, we won the game. We won the game, which/as we expected. The number of the visitors, as/which we
She is a girl __w_h_o_/_th_a_t is very slim and attractive. She is a girl ___(w_h_o_/t_h_at) we often talk about
I, who am your best friend, believe in you.
• Compare: •China has hundreds of islands,
the largest of which is Taiwan. I like the house of which the roof is blue.
the roof of which whose roof
I need this man, who can speak English.
This is such an interesting book _a_s__ interests all students.
This is so difficult a question _a_s__ no one can work out.
He is so popular a person _a_s_ we all like to talk with.
youngest son than to the others, _____, of Dcourse, made the others envy him. (2004, 天津卷)
A. who
B. that
C. what
D. which
2. Carol said the work would be done by October, __D___
He has three sons who/that are doctors.
He has three sons, two of whom are doctors.
He has three sons, all of whom are doctors.
He has three sons, none of whom are doctors.
I bought the same car _a_s_ he is driving.
What is the difference between the restrictive attributive clauses and the non-restrictive clauses?
1.形式不同
限制性定语从句和先行词之间不用逗号隔开； 非限制性定语从句与先行词之间要用逗号隔开。