助动词用法及练习

be动词，情态动词，助动词do/does的用法区别及练习

助动词，顾名思义就是帮助动词完成疑问及否定的，本身没有什么含义。主要的助动词有be,do,will,have等，其用法详述如下：

一、⑴由连系动词am，is，are构成的句子：变一般疑问句时把am，is，are

提到句子的前面，句尾用问号即可。变否定句时直接在am，is，are后面加not 即可。例如：

肯定句:He is a student.

一般疑问句: Is he a student

否定句: He is not a student.

画线提问: 对he提问: Who is a student

对 a student 提问: What is he

(2)was 是am,is的过去式，were是are的过去式，若句子中有以上两词时，变疑问句及否定句方法与（1）相同。

二、(1) 由情态动词can, may,will ，shall等构成的句子: 变一般疑问句时把can, may,will ，shall提到句子的前面,句尾用问号即可.变否定句时直接在can,may,后面加not即可. 例如:

肯定句: She can swim.

一般疑问句: Can she swim

否定句: She can not swim.

画线提问: 对she提问: Who can swim

对swim提问: What can she do

（2）could,might,would,should是can,may,will,shall的过去式，若句子中有以上两词时，变疑问句及否定句方法与（1）相同。

三、（1）由行为动词构成的句子: 需要加助词do或does. 变一般疑问句时把do/does放在句子前面. 变否定句时把don’t/doesn’t放在动词的前面。要注意观察动词的形式并对号入座。一般疑问句和否定句的动词三单式都要变回原型。

play-----do plays-----does

例如:

肯定句: They play football after school. He plays football after school.

一般疑问句: Do they play football after school Does he play football after school

否定句: They don't (do not) play footba ll after school. He doesn’t’ play football after school.

画线提问: 对they/he提问: Who plays football after school

对play football提问: What do they do after school What does he do after school

对after school提问: When do they play football When does he play football

（2）did是do和did的过去式，变一般疑问句时把did放在句子前面. 变否定句时把didn’t放在动词的前面, 要注意观察动词的形式并对号入座。一般疑问句和否定句的动词都要变回原型。

四、(1)由have,has构成的现在完成时句子，变一般疑问句时把have,has提到句子的前面，句尾用问号即可。变否定句时直接在have,has后面加not即可。例如：

肯定句：He has read today’s newspaper.

一般疑问句: Has he read today’s newspaper.

否定句: He has not read today’s newspape

画线提问: 对he提问: Who has read today’s newspaper

对today’s newspaper提问: What has he did

(2)had是have和has的过去式，在构成的过去完成时句子中，变一般疑问句时把had提到到句子的前面，句尾用问号即可。变否定句时直接在had后面加not即可。

(3)若have,has,had没有出现在完成时的句子中，则当实义动词对待，请参考实义动词的用法。

五、第一人称I，we在变疑问句时，应变为第二人称you。“I am, you /we /they are”这是初一最简单的固定搭配，不应再唠叨了吧！

六、is,has,does用于第三人称的现在时态，was用于第三人称的过去时态。

针对性练习

按要求改写句子：

have been to Beijin(一般疑问句)

______ ______ __________ to Beijin

can see some birds.(一般疑问句)

______ ______ see ______ birds

designs clothes.(一般疑问句)

______ he ________ clothes

were s ome flowers on the teachers’ desk.(一般疑问句) ______ ______ ______ flowers on the teachers’ desk were some apples on the tree.(否定句)

There ______ ______ ______ apples on the tree.

think he is very old.(否定句)

I ______ think he ______ very old.

colour it green.(否定句)

______ ______ colour it green.

had lunch(变否定句)

______ _______ ______ __________.

may have some hot dogs.(一般疑问句)

_______ ______ ______ ______ ________.

aren’t any pears in the box.(同义句)

There are ______ pears in the box.

sign means “No smoking”.

What ______ this sign _________

has already written the letter.(改为否定句)