1.be able to do 能夠……、有能力……
【例句】Unless you change your mind (=If you don't change you mind), I won't be able to help you.
除非你改變你的想法，否則我不能幫助你。
【總結(jié)】be able to 則主要指具體做到了某件事的能力，其形式主要是靠be 發(fā)生變化。
【詞語辨析】can，could，be able to
①can could 表示能力;可能(過去時(shí)用could)，
只用于現(xiàn)在式和過去式(could)。be able to可以用于各種時(shí)態(tài)。
They will be able to tell you the news soon. 他很快就能告訴你消息了。②只用be able to
a. 位于助動(dòng)詞后。
b. 情態(tài)動(dòng)詞后。
c. 表示過去某時(shí)刻動(dòng)作時(shí)。
d. 用于句首表示條件。
e. 表示成功地做了某事時(shí)，只能用was/were able to，不能用could.
He was able to flee Europe before the war broke out.
= He managed to flee Europe before the war broke out.
注意：could不表示時(shí)態(tài)
①提出委婉的請求，(注意在回答中不可用could)。
—— Could I have the television on?
—— Yes, you can. / No, you can't.
②在否定，疑問句中表示推測或懷疑。
He couldn't be a bad man.
他不大可能是壞人。
2.be about to do...when 就要做某事時(shí)，突然……
【例句】I was about to wash my face when he came back.
當(dāng)他回來的時(shí)候我正要去洗臉
【總結(jié)】be about to do...when 時(shí)態(tài)問題及如何解題when在這里的用法很特別，它是并列連詞=and then
——這一點(diǎn)很重要!
記住一下規(guī)律：
...was/were about to do...when sth. did...
=...was//were on the point of doing...when sth. did...
3.be about to do 準(zhǔn)備做……
【例句】He raised his hat and was about to speak, but she gave him the go-by as though she had never seen him before. 他摘下帽子，剛要講話，她卻根本不理他，好像以前從未見過他似的。
【總結(jié)】be about to do表示即將、馬上、眼瞅著要做某事;不接時(shí)間狀語。
【詞語辨析】be to do sth.和will do sth.和be about to do sth., be going to do
be to do表示一種命中注定會(huì)發(fā)生的事情
will do 表示一種個(gè)人意愿(將會(huì)做某事，這個(gè)主要和be going to do區(qū)分)
be about to do表示即將、馬上、眼瞅著要做某事
be going to do 1)如果主語是人，那它的意思是：打算好了做某事
2)如果是物作主語，那它的意思是：將要……
It is going to rain soon. 要/快下雨了。
4.be absent from 不在、缺席
【例句】You should not be absent from class. 你不應(yīng)當(dāng)曠課。
【拓展】absent是形容詞，attend是動(dòng)詞,直接接名詞
如：attend a lecture 聽講課
attend church 去教堂
attend (at) a wedding 出席婚禮
5.be absorbed in 沉迷于……、迷戀于……
【例句】The humour of it is not to be absorbed in a hurry. 其中的幽默不是一下子能領(lǐng)會(huì)的。
【例句】be absorbed by 被……吸收
be absorbed with 專心致志于; 全神貫注于
be absorbed in study 專心研究，埋頭學(xué)習(xí)
be absorbed in a book 埋頭看書
be absorbed in a work 埋頭工作
Judith lay on the small sofa, _____in her book.
A. being absorned B. absorbed C. to absorb D. absorb
答案：B 題意：朱迪思網(wǎng)在沙發(fā)上專心致志地看書
【解析】上面的句子absorbed前面省略了主語Judith，可以把它分為2個(gè)分句：Judith lay on the small sofa and Judith was absorbed in her book. 這樣就看明白。