英语学习先从简单点单词句子开始，同时语法也很重要！今天看看be动词用法及怎么把肯定句变否定句，如何把陈述句变疑问句！
口诀：
我用am，你用are，is连着他，她，它;
单数名词用is，复数名词全用are.
变疑问，往前提，句末问号莫丢弃
变否定，更容易，be后not莫忘记
疑问否定任你变，句首大写莫迟疑
be动词用法
“Be”除了原形的“be”之外，还有另外七种形式：am, is, are, been, being, was, were.
在句子中，“be”可以是主动词(The Principal Verb)或助动词(The Auxiliary Verb).
当主动词时，“be”在性质上属于接系动词(The Linking Verb), 后面要有名词、形容词、地方副词或短语作补足语(The Complement)。例如：
1. The man is a science teacher.
2. Mary's new dresses are colourful.
3. I have been there before.
4. Mother is in the kitchen now.
这四个都是陈述句，可以变成疑问句，方法简单，把主语和“be”或助动词对换位置即可：
5. Is the man a science teacher?
6. Are Mary's new dresses colourful?
7. Have I been there before?
8. Is mother in the kitchen now?
当“be”要在祈使句中出现时，它必须借重助动词“do”或“don't”之助，如：
9. Don't be silly!
10. Do be obedient!
11. Don't be a fool!
“Be”有两种缩写法，如下：
He's not...../He isn't....
You're not...../You aren't...
但“am not”的缩写法只有一个：
I'm not.
谈过了“be”作主动词的功能，现在看看“be”作助动词时，有些什么用法：
1.“Be 现在分词”以组成进行式时态(Continuous Tenses)，如：
Tony's maid is washing his new car.
The children are playing in the field.
Samuel was eating when I came in.
We have been living here since 1959.
2.“Be 过去分词”以组成被动语态(The Passive Voice),如：
Her money in the drawer was stolen.
A number of good jobs are taken up byforeigners.
David studied in Taiwan but has been trained as a language lecturer in America.
Can all the wonderful birds be found in our Bird Park?
The disobedient boy was told to stand out- side the classroom.
Steps are being taken to reduce traffic con- gestion during peak hours.
Dishonest students will be immediately dealt with.
拓展
一、肯定句变否定句：加not
She works here . She doesn't work here .
I have been in China . I haven't been in China .
I am a student . I'm not a student .
LiLei has ever been to Guiling . Li Lei hasn't been to Guiling .
She is going to do her homework . She isn't going to do her homework .
use to疑问句和否定句有两种方式：1 像其它行为动词过去时一样,借助于助动词did,used恢复原形use.2 直接用used,提前构成疑问句,后面加not 构成否定句
二、陈述句变疑问句
1·先找系动词be:am,is,are,was,were。找到后提前变人称(第一人称变第二人称，第三人称不变)加问号。例:you are a pupil变Are youa pupil?
2找不到系动词再找情态动词:can may must will shall need could should would might 找到后变人称(第一人称变第二人称，第三人称不变)加问号。例:They will go to school.变Will they go to school?
3找have got,has got ,had got.找到后把have has had 提前，got留在原地不动。变人称加问号 例:You have got a TV.变Have you got a TV?
4添加助动词:do does did,把助动词加在最前面 ，例:I play with a dog变Do you play with a dog.以上四种方法变成疑问句之后把里面的动词都变成原型。
一般疑问句及肯定否定回答
1、问句： Is this your English book？
肯答： Yes，it is.
否答： No，it isn`t.
2、 问句： Are these your English books？
肯答： Yes，they are.
否答： No，they aren’t.
3、 问句： Can you speak English?
肯答： Yes，I can.
否答： No，I can’t.
4、 问句： Do your parents like English？
肯答： Yes，they do.
否答： No，they don’t.
5、 问句： Can you speak English?
肯答： Certainly \ Of course.
否答： Sorry, I can’t.
6、问句：May I watch TV after supper?
答：Yes, you may. / No, you mustn't.
7、 问句：May I stop here?
答：No, you mustn't.
8、问句：Must I finish my homework before eight o'clock?
答：Yes, you mus.
9、问句：Must I attend the meeting?
答：No, you needn't(No, you don't have to). You can ask Tom to go instead.
10、问句：Need we stay behind after school?
答：Yes, you must.
11、问句：Need he go now?
答：No, he needn't.
