Lesson 17 always young重点语法
l 表示必须要做的事情,意思是”必须,必要”,一般表示现在或将来的情况.主语是第一人称I或WE时,表示说话人认为有必要或有义务做某事;主语是第二 三人称you, they, he, she等时,表示说话人要求或命令别人做某事.
You must work hard at school.
I must go now.
l 回答由must提出问题,否定回答用needn't,意思是”不必”.
Must I go now? No, you needn't.
l 表示对现在情况的肯定推测,用于肯定的陈述句中,意思是”想必,一定”(否定句和疑问句要换成can, 在疑问句中表示”...可能吗?”,在否定句中表示”...不可能.”)此时,must后面接系表结构,进行时或表示状态的动词原形.
eg: He must be a teacher.
He must be spending holidays with his family.
He must have a lot of money.
Can he be a teacher? He can't be a teacher.
l 表示对过去情况的肯定推测,用于肯定的陈述句中,意思是”想必,一定”.
eg: You must have been on a trip or on a visit to your relatives.
如果时否定形式,则是另外的意思了: must not 表示”禁止.不许”