the fifth chapter → chapter five 第五章.3
a. be可构成进行时态、被动语态和复合谓语：
She is writing a novel. 她在写小说。（进行时态）
What have you been doing? 你干什么来着？（进行时态）
She was given a warm welcome. 她受到热烈欢迎。（被动语态）
The case is being investigated. 这案子正在调查。（被动语态）
How are you to explain all this? 这一切你怎么解释？（复合谓语）
b. have可构成完成时态和完成进行时态：
She'd (had) been out shopping. 她出去买东西了。（完成时态）
They have set up a network of financial advice centers. 他们建立了一个金融咨询中心网。（完成时态）
She's (has) been doing some research work. 她一直在做研究工作。（完成进行时）
That was the letter we'd (had) been expecting. 这正是我们在期待的信。（完成进行时）
c. do可构成疑问句、否定句，用于强调或代表前面动词以避免重复：
When did she get there? 她什么时候到的？（疑问句）
He doesn't know anything about it. 他对此一无所知。（否定句）
Do stay for a couple more days. 务请再待两三天。（强调）
He speaks English better than I do. 他英文讲得比我好。（代表前面动词）
2) shall，will，should，would：
这几个词都可用作助动词，但有时有一定的意思，接近一个情态动词：
a．will 主要用来构成将来时态，可用于多个人称（will not常可紧缩为won't/wəʊnt/）：
When will you be back? 你什么时候回来？
I'll let you know in a day or two. 一两天后我将通知你。
They won't let you down. 他们不会让你失望的。
b. shall主要用在第一人称作主语的问句中，征求对方意见：
Shall I wait for you? 我要不要等你？
Shall we meet again tomorrow? 明天咱们要不要再碰头？
How shall I help you? 我该怎么帮助你？
在英国，也有人把它用于第一人称的肯定句或否定句（在口语中shall not可紧缩为shan't /ʃɑːnt/）：
I shall often be coming to Pisa. 我会时常到比萨来。
We shall read about it tomorrow. 明天我们就会读到这消息了。
We shan't be coming back today. 我们今天不回来了。
c. would主要用来构成过去将来时态，可用于多个人称：
I knew you would agree. 我知道你会同意的。
I asked if he would come and join us. 我问他是否愿意来参加我们的活动。
I said that I would arrange everything. 我说我会安排一切的。
也可用来提出请求、看法等：
Would you please look over my essay? 可否劳驾看一遍我的文章？
What would you like? 你愿意要什么？
I'd go there with you. 我愿和你一道去。
还可用在虚拟条件句中：
I would do it if I could. 如果我有能力我会这样做的。
If he were in town, he'd help. 如果他在城里，他会帮忙的。
d. should间或还用来构成过去将来时（但大多数人已改用would），用在第一人称后：
We (I) never thought we (I) should (would) see you again. 我们以为不会再见到你了。
The weather report said that we should have rain. 天气预报说会下雨。
目前更多用来表示“应当”（a）或用在某些从句中（b）：
a. You should do it for your own good. 为了你自己好，你应当去做。
Why should I pay him? 我为什么该付他钱？
b. He wrote, suggesting that we should go to Paris. 他来信了，建议我们去巴黎。
It will be better that he should be out of France. 他离开法国会好一些。
It is dreadful that they should be so miserable. 他们竟然这样悲惨，太可怕了。
We hid it so that he should not see it. 我们把它藏了起来以免被他看到。
