初中英语必考语法知识点:must/might/could/can't1. must(1)must 表示主观看法,意为“必须”。如:You must stay here until I come back.Must I hand in my homework right now?对must引导的疑问句,肯定回答为must,否定回答为needn’t 或don’t have to .如:—Must I finish my homework?—No, you needn’t.(2)must也可以表示有把握的推测,意为“ 一定,肯定”,用于肯定句。如: The light is on, so he must be at home now.其否定形式mustn’t表示“禁止,不许”。如:You mustn’t play with fire.You mustn’t be late.2. could(1)can的过去式,意为“能、会”,表示过去的能力。如:He could write poems when he was 10.(2)could在疑问句中,表示委婉请求的语气,此时could没有过去式的意思。如:Could you do me a favour?—Could I use your pen?—Yes, you can.(注意回答)3. mightmight为may的过去式。might表示推测时,表示可能性低于may(此时might没有过去式的意思),当请求讲时,比may的语气更委婉。He is away from school. He might be sick.Might I use your dictionary?4. can(1)表示能力,一般译为“能、会”,尤其指生来具备的能力。如:She can swim fast, but I can’t .(2)表示许可,常在口语中。如:You can use my dictionary.(3)表示推测,意为“可能”,常用于否定句和疑问句中,此时can’t译为“不可能”。如:—Can the news be true?—No, it can’t be our teacher. He is on a visit to the Great Wall.