就能告诉你消息了。
2be able to a. 位于助动词后, b. 情态动词后, c. 表示过去某时刻动作时, d. 用于句首表示条件,
e. 表示成功地做了某事时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. 9.---We'll have to tie ourselves to our beds so that we won't float away in our sleep!
must和have to用法比较讲解:
1must表示“必须”must not(mustn't)表示“不应该”
等。在回答带有must的问句时need not(needn't)或don't have to 表示“不必”must not (mustn't)。 The work must be finished as soon as possible.这件工作必须尽快完成。 You mustn't speak like that.你不能那样说话。—Must I be home before eight o'clock? 8点之前我必须回家吗—Yes, you must./No, you needn't./No,
you don't have to. 是的/不
2must表推测
①一般只用于肯定句中 There must be some mistakes.
肯定有一些错误。 You must be very tired.你一定很累了。
②如果表示对过去事情的推测"must+完成时"。 You must have left your
umbrella in the theatre.你一定把雨伞丢在剧院里了。 His car is still here.
He must have gone by bus.他的车还在这里
③当must表推测之意时can not而不用must not。 He can't have
been to your home. He doesn't know your address.他不可能到过你家
他不知道你的住址。 What can he be doing at this time of night?夜晚都到
这个时候了?
3must表必然性 You must catch cold if you don't put on more clothes.如果你不多穿些衣服 All men must die.人固有一死。 Truth must be out.真相总
会大白。
4have to表示“必须”must很接近但must表示的是说话人的主观看法have to 表示的却是客观需要。 I have to go now.我得走了。
I must go now.我必须走。 You have to work hard to make a living.为了谋生你就得努力工作。 You must do what I tell you.你必须按
照我告诉你的去做。
5have to 有更多的时态形式must只有现在时形式。We had to be there at 8.我们得8点到那里。 I shall have to go to school tomorrow.明天我得去上学了。
so that 以便 I get up early today so that I can catch the first bus to work. 我今天早起以便能赶上去上班的头班车。
10.Without gravity, our bodies may get weak,so we'll have to do exercises every day.
Without gravity=If there is no gravity, our bodies may get weak. 如果没有万有引力
11.I'll have to wear a spacesuit to help me breathe because there's no air on the Moon.
①wear, dress, dress up, in, put on的用法小结: 都含有“穿、戴”之意