二、情态动词概要.ppt

情态动词 第二章 情态动词(Modal Auxiliary) 情态动词的特征 本身有词义, 但不完整, 因此不能单独作谓语, 只能与V构成谓语。 情态动词后接动词原形。 情态动词不随人称而变化。 其否定形式为：情态动词+not can------cannot may-----may not 疑问式 May I come in? Can you lend me some money? 注意：have to Do you have to go today? 情态动词在肯定句中的用法（1） Can can 表示体力或脑力方面的“能力、技能”或根据客观条件能做某种动作的“能力”。 Can you drive? I can move the store. You can use a different material instead. Could 表示过去的能力或可能性。 I could run very fast when I was young. I couldn’t understand what he said at all. 代替can 用于现在动作，但语气更委婉。 Could I use your bike? You could do it this way. 情态动词在肯定句中的用法（2） may 许可、可以 May I ask you a question? You may take the boy there. 表示说话的猜测，认为某事“或许、可能”发生。 We may call on you this evening. What he said may be true. might . may 的过去式 He told me he might come. (may 的过去式) might 也用来表示现在的事情，只是语气更弱、可能性更小。 He might know her address. Might I give you a piece of advice? (比may 更委婉) 情态动词在肯定句中的用法（3） must 必须、应当 You must finish the work before 4 o’clock. Must we go today? --Yes, you must. --No, you needn’t. 回答must引出的疑问句时, 否定式只能用needn’t. must , have to 的区别： must强调主观, “必须”, have to强调客观,“不得不” We must ask for permission if we do it. It’s raining heavily, we can’t go now, I think we’ll have to wait till the rain stop. 情态动词在肯定句中的用法（4） shall 用于第一人称的疑问句中，表示征求对方意见。 What shall I do now? Shall we go together? should 应当 You should listen to the doctor’s advice. 表示“推测、可能” They should get home by now. (应该到家) ought to 有义务、必要做…… You ought to finish your work before you go home. 表示非常可能的事 His father ought to know his address. 情态动词在肯定句中的用法（5） will would 主要用于第二人称的疑问句中，表示说话人向对方提出请求。would 比 will 更客气。 Will you help me? Would you like some tea? 情态动词在肯定句中的用法（6） need “需要”,主要用于疑问、否定句中. Need we do it again? ------No, you needn’t do it again. I think he needs to do it again. (实义动词) 情态动词在肯定句中的用法（7） had better (最好) would rather (宁愿) 否定式：had better not V, would rather not V 疑问式：Had you better…? Would you rather…..? I would rat