文丨陈德永
英语中的助动词：am / is / are / will / have / has / was / were / had / would / do / does / did，到目前为止，我们已经总结了英语中全部助动词用法，我发现：在否定句和疑问句中，助动词就会大显身手，它们的作用是：帮助主动词完成“时间和数”的概念表达。今天我们先看助动词在否定句中的作用。
英语的否定句，都是在助动词后面 + not 来构成，not 都可以缩写为 n’t ，am 后面 not 不这样缩写，而是写成 ain"t，但是这种用法极其不正式，只有古英语中反问才会见到 Ain"t I ......？ 所以大家在现行教科书中见不到。
下面我们就看看助动词后加 not 以实现否定的例子，为了方便大家对比，我们一个肯定句、一个否定句来排版：
am
I am busy typing. 我们正忙于打字。
I am not busy typing. 我不是忙于打字。
非要缩写的话，可以写成 I"m not busy. 吧。
is
He is singing. 他在唱歌。
He is not singing. 他不是在唱歌。
= He"s not singing. = He isn"t singing.
are
You are joking. 你在开玩笑
You are not joking. 你不是在开玩笑。
= You"re not joking. = You aren"t joking.
又如：
We are waiting. 我们在等。
We are not waiting. 我们不是在等。
We"re not waiting. =We aren"t waiting.
will
I will go with you. 我要和你一起去。
I will not go with you. = I won"t go with you. 我不会和你一起去
have
I have finished it. 我已经完成。
I haven"t finished it yet. 我还没有完成。
has
She has already left. 她已经了开了。
She hasn"t left yet. 她还没有离开。
was
He was late this morning. 他今天上午迟到了。
He wasn"t late this morning. 他今天上午没有迟到。
were
We were in Shanghai yesterday. 昨天，我们在上海。
We were not in Shanghai yesterday. 昨天，我们没在上海。
= We weren"t in Shanghai yesterday.
had
When I got to school, the class had begun. 我到学校时，课堂已经开始了。
When I got to school, the class had not begun. 我到学校时，课堂还没有开始。
=When I got to school, the class hadn"t begun.
would
He said he would come. 他（当时）说，他会来的。
He said he would not come. 他（当时）说，他不会来的。
=He said he wouldn"t come.
do【不同了】
和此前的例子不同了，在前面的句子中，肯定句中也有助动词，而 do 只是在否定句、疑问句中才出来帮忙，肯定句中不需要，除非为了强调谓语。比如：
I do my homework every day. 为了让大家区分 实义动词的 do ，专门举这个例子，这里的 do 不是助动词，而是一个有实际意义的实义动词，意为“做作业”的“做”。
肯定：I do my homework every day.
否定：I do not do my homework every day. = I don"t do my homework every day.
上面的否定句中，前面的 do 是助动词，第二个 do 是“做作业”的“做”。
does，为了易懂，只把上例略作改变：
肯定：He does his homework every day. 此句中 does 是实义动词，意为“做作业”的“做”，只因主语是“单三”才加了es。
否定：He does not do his homework every day. = I doesn"t do his homework every day.
上句中，前面的 does 是助动词，以帮助后面的实动词 do，帮助其完成“时和数”的概念表达，即主语是“单三的”，时间是“平时的” 。
did
肯定：He did his homework yesterday. 此句中 did 是实义动词，意为“做作业”的“做”，只因时间是昨天，采用了过去式 did 。
否定：He did not do his homework yesterday. = I didn"t do his homework yesterday.
上句中，前面的 did 是助动词，以帮助后面的实动词 do，帮其完成“时”的概念表达，即时间是“昨天” ，过去时中，实动词和助动词都不区分 “数”。
表示“是、存在”：be 的时态变化，重点！
动词的屈折变化，学英语的难点，更是重点！重点！
would 只是 will 的过去式？没那么简单！
助动词 shall、will 和 should、would 的用法（重点，必须掌握）
