情态动词也可称为"情态助动词 (Modal Auxiliaries)"，因为它和基本助动词(be, do, have)都属于助动词类。 * 情态动词和其他动词连用，可表示说话人的语气。 * 情态动词可表达建议、要求、可能和意愿等。 * 情态动词没有人称和数的变化。 * 常用的情态动词有：can, could, may, might, must, shall, should, will, would 这九大情态动词；其他的还有ought to, need, dare 等。 其实我们这里谈的情态动词，它的特征用法，有许多方面和助动词是一样的（请参阅 《英文语法拉杂谈》助动词）；但为了方便阅读，因此即使相同的部份，这里也同样列 出。 一、情态动词的变化：(情态动词could，动词 to work) 1.1 简单型(Simple)：表示现在或将来的状态 I could work (动词不可加 to ，如：to work。下同) you could work he could work she could work it could work we could work they could work 1.2 完成式型 (Perfect)：表示过去的状态 I could have worked (动词是 have + v-ed 过去分词。下同) you could have worked he could have worked she could have worked it could have worked we could have worked they could have worked 1.3 进行式型 (Continuous)：表示现在或将来还在进行的状态 I could be working (动词是be + v-ing 现在分词。下同) you could be working he could be working she could be working it could be working we could be working they could be working 1.4 完成进行式型 (Perfect Continuous)：表示过去正在进行的状态 I could have been working (动词是 have been + v-ing 现在分词。下同) you could have been working he could have been working she could have been working it could have been working we could have been working they could have been working 二、情态动词的疑问句： 只要将情态动词移到主语(Subject)的前面，句尾加上问号。这样就成了疑问句。 1. She can work.(主语she, 情态动词 can，动词 work) Can she work ? (这就是疑问句） 2. He would be working. (主语he, 情态动词 would，动词 be working) Would he be working ? 3. They should have worked. (主语they, 情态动词should, 动词have worked) Should they have worked ? 4. I could have been working. (主语 I, 情态动词 could, 动词 have been working) Could I have been working ? 三、情态动词的否定句： 在情态动词的后面加上 not 就成了情太动词否定句。 1. She can work. She cannot work. (注意：can 和 not 须连在一起）(这就是否定句) 2. He would be working. He would not be working. (would not) 3. They should have worked. They should not have worked. (should not
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