be类助动词通常与情态动词表示推测与可能性时 be类助动词在表示推测与可能性时，通常与情态动词一同使用，以表达不同层次的推测和可能性。以下是对其用法的辨析： 首先，要明确be类助动词本身并没有具体的含义，而是与其他动词或短语一同构成谓语，表示时态、语态或情态等。当与情态动词结合使用时，它们共同表达某种推测或可能性。 在表示推测时，be类助动词常与情态动词如may、might、could、should等连用。这些情态动词本身就具有表示推测的含义，而be类助动词则帮助构成完整的谓语结构。例如，“She may be at home.”（她可能在家。）这句话中，may表示推测，be则作为助动词与may一同构成谓语，表达了一种可能性。 另外，be类助动词还可以用于表示不同程度的可能性。例如，might比may所表示的可能性更小一些，带有更多的不确定性；could则既可以表示推测也可以表示能力，具体含义需要根据语境来判断；should除了表示推测外，还常常带有一种建议或责任的意味。 新概念英语第三册单词 初中英语单词mp3 新概念英语视频下载 七年级下册英语阅读理解 需要注意的是，当be类助动词与情态动词连用时，整个谓语结构所表达的含义是综合性的，既要考虑情态动词的含义，也要考虑be类助动词所表示的时态、语态等因素。因此，在理解和使用这种结构时，需要综合考虑各方面的因素。 此外，还需要注意区分系动词be和助动词be的用法。系动词be主要用于构成“主系表”结构，表示主语的状态或特征；而助动词be则主要用于构成谓语的其他成分，如进行时态、被动语态等。在表示推测与可能性时，我们主要关注的是助动词be的用法。 综上所述，be类助动词在表示推测与可能性时，通过与情态动词的结合使用，可以表达不同层次的推测和可能性。在理解和运用这种结构时，需要综合考虑情态动词和be类助动词的含义和用法。 一、选择题 1. He _____ be at the library right now. He usually studies there after lunch.    A. must      B. can      C. might      D. should 2. They _____ have left early, because the car is not in the driveway.    A. may      B. must      C. could      D. would 3. She _____ not come to the party tonight. She said she wasn't feeling well.    A. will      B. might      C. should      D. must 4. It _____ be John who broke the window. He was the only one in the room at that time.    A. could      B. might      C. should      D. must 5. They _____ still be at the cinema. The movie just started ten minutes ago.    A. can      B. may      C. must      D. ought to 二、填空题 1. She hasn't replied to my email yet. She _____ be busy with something else. 2. The light in the office is still on. They _____ have forgotten to turn it off. 3. I'm not sure if he will come to the meeting. He _____ decide at the last minute. 4. The strange noise in the night _____ have been a cat or a dog. I'm not sure. 5. The traffic is very heavy today. They _____ arrive late for the appointment. 三、改错题 1. She can't be in the office. She told me she was going to the bank. (改为更确定的推测) 2. He might not have seen the notice on the board. (改为更可能的推测) 3. They should be at the restaurant by now. They left early. (改为更不确定的推测) 4. It must have been a thief who stole the jewelry. There were no signs of forced entry. (改为可能性更小的推测) 5. He could be the new manager. He has a lot of experience in the field. (改为更肯定的推测)