必修3 unit1 情态动词Ⅰ

2. Mr. Bush is on time for everything. How ____ A it be that he was late for the opening ceremony? A. can B. should C. may D. must
3. should
表示义务、劝告、建议。 意为 “应该”。
Eg: You should keep your promise.
4. may 与might的异同
1. may might和表示“许可”或“请求”，表示没有把 握的推测 。 E.g: They may be in the library now. 2. might 表示推测时，不表示时态，可能性比may小。
情态动词 ( modal verbs)
情态动词表说话人的某种感情 或语气，对某一动作或状态的 某种态度。表示“需要、可以、 必须、应当”等。
1. must
1. mustn’t 表示 “不准”，含命令口气。
Eg: Children mustn’t speak like that to their parents.
E.g Could I use your dictionary? Yes, you can/ No, you can’t
B be a policeman, for he’s much too short. 1. Michael ____ A. needn’t B. can’t C. should D. may
2. can 与could的异同
1.Can和could用于疑问句或否定句中，表推测：
1) Can she be in the computer center?
2) I though what he said could not be true.
2. 表示“请求”、“允许” 时，常用 could 代替 can 使语气更委婉，回答时用can
2. must用于肯定句中，表有把握的推测， 意为“一定”。
Eg: He must be watering the flowers in his garden. 3. 回答 must 所在的一般疑问句时，否定回答用 “needn’t” 或“don’t have to”. Eg: ---Must we finish the work tomorrow? ---No, you needn’t/ don’t have to, but you must finish it in three days.
5. shall
1. Shall 与第一、三人称连用，用在疑问句中时， 表说话人征求听话者的允诺,建议。
Eg: 1) Shall we begin our discussion?
2) Shall the driver wait?
Exercise:完成讲学稿上面相关练习
can 和 may 的异同
1. may表示请求、允许时Biblioteka Baidu比can较为正式,
Eg: May I come in? Yes, you may / No, you may not 2. may表示说话人推测时，通常只用于肯定句和否定句中。 而，can用于否定句和疑问句中。
Eg: I believe the man is from England. But I may be wrong (may 的肯定句） It may not ( can’t) be him to break the window. (否定 句） Can it be Tom to break the window? (can 的疑问句）
E.g. It might be Tom, who breaks the window.
3. May you +动词原形 表“祝愿” ,might不能放在句首 Eg: May you success.
1.Sorry I'm late. I _____ A have turned off the alarm clock and gone back to sleep again. A. might B. should C. can D. will 2.Peter _____ B come with us tonight, but he isn’t very sure yet. A. must B. may C. can D. will