A．单句填空
1．—Can't you stay a little longer?
—It's getting late. I really________ go now. My daughter is home alone.
答案 must [句意：——你就不能多待一会儿吗？——天越来越晚了。我现在真的必须走了。我女儿一个人在家里呢。根据答语中的“It's getting late.”以及“My daughter is home alone.”可知，这里表示必须离开，故用must。]
2．You________ be careful with the camera. It costs!
答案 must [句意：你一定要小心这个相机。它很贵的！根据语境可知，此处表示“一定”，故用must。]
3．You________ feel all the training a waste of time, but I'm a hundred percent sure later you'll be grateful you did it.
答案 may [句意：你可能感觉到所有的培训都是浪费时间，但是我百分之百的确信最后你将感谢你所做的这一切。根据句子中的“but I'm a hundred percent sure later you'll be grateful you did it”可判断出，表示对前面情况的一种推测，表示“也许，可能”，故用may。]
4．—I've prepared all kinds of food for the picnic.
—Do you mean we ________bring anything with us?
答案 needn't [句意：——我已经为野餐准备好了各种食物。——你的意思是说我们不必再带任何东西了吗？根据上下文可知此处表示“不必”，故用needn't。]
5．My book, The House of Hades, is missing. Who________have taken it?
答案 could [句意：我的书《哈迪斯的房子》丢了，谁会把它拿走呢？根据句意可知此处表示推测，又因是疑问句，故用could。]
6．She often appears as a young girl on stage although she ________be at least 55 years old.
答案 must [句意：在舞台上，她经常像小女孩，虽然至少有55岁了。此处表示肯定推测，故用must。]
7．Being constantly exposed to advertisement is annoying, but it________be pleasant sometimes.
答案 can [句意：经常接触广告很烦人，但有时也令人愉快。此处表示客观的可能性，“有时会”，故用can。]
8．Liza________well not want to go on the trip—she hates traveling.
答案 may/might [句意：莉莎很可能不想去旅游——她讨厌旅游。根据设空处后的well可知本空填may/might。may/might well do sth.意为“很可能做某事”。]
9．One of the National Health Regulations is that public schools ________actively create conditions for sports facilities opened to the public.
答案 shall [句意：全民健身条例内容之一是公立学校需积极创造条件向公众开放体育设施。根据句意可知，此处表示规则、规定，且用于第三人称肯定句中，故用shall。]
10．—Amazing! You________wear slippers at school.
—Don't you know it's a fashion?
答案 should [句意：——太奇怪了，你竟然在学校穿拖鞋。——难道你不知道这很时尚吗？根据语境表示一种惊讶，故用should。]
B．单句改错
1．—Sorry, Mum! I failed the job interview again.
—Oh, it's too bad. You must have made full preparations.
________________________________________________________
答案 must→should [句意：——对不起，妈妈，我工作面试又失败了。——哦，太糟糕了，你本应该做充分准备。根据句意可知，此处表示“本应该做某事而实际上没做”暗含对对方的责备，故用should，而must have done表示“过去一定做了……”，与句意不符。]
2．Sometimes people simply mustn't trust anymore.
________________________________________________________
答案 mustn't→can't [句意：有时候人们只是不能再相信(他人)了。can't不能，符合句意。mustn't不准；禁止。]
3．Although you must find bargains in London, it's not generally a cheap place to shop.
________________________________________________________
答案 must→can [句意：虽然你在伦敦可能会买到减价品，但通常那儿不是一个能买到便宜货的地方。must意为“一定”，此处表示客观的“可能性”，故把must改为can。]
4．Should I have a word with you? It won't take long.
________________________________________________________
答案 Should→Can/May [句意：我可以和你说句话吗？不会耽误很长时间。根据句意可知此处表示请求，“可以”，should为应该，故把Should改为Can/May。]
5．Life is unpredictable; even the poorest must become the richest.
________________________________________________________
答案 must→may/might [句意：生活是不可预测的，即使是最贫穷的人也可能成为最富有的人。根据句意可知本空表示把握性不大的推测，故把must改为may/might可能。]
6．—These grapes look really beautiful.
—They can! See the price $3.99 a pound. Very expensive, aren't they?
________________________________________________________
答案 can→should [句意：——这些葡萄看起来很漂亮。——它们应该这样！看价钱，3.99美元一磅，太贵了，是不是？根据句意可以猜出葡萄看起来好是应该的，因为价格贵。]
7．I mustn't thank you too much because without your help I wouldn't have won the first prize.
________________________________________________________
答案 mustn't→can't [句意：我都不知道该怎么谢你了。没有你的帮助我不会获得一等奖。can't与too连用，意为：再……也不为过。]
8．Nuclear energy must be really dangerous at times even though it's a kind of nice energy in general.
________________________________________________________
答案 must→can [句意：尽管核能在总体上是一种不错的能源，但它有时可能真的会很危险。can用于肯定句可表示客观上的可能性，意为：有时会，可能会。]
9.We can't imagine that two children shall be killed by the washing machine of their house.
________________________________________________________
答案 shall→should [句意：我们无法想象两个孩子竟然被家里的洗衣机绞死了。should表示“竟然”。]
10．One of our rules is that every student must wear school uniform while at school.
________________________________________________________
答案 must→shall [句意：我们的规定之一是学生在学校时需要穿校服。在明文规定中，常使用shall来表示规定做的事情。]