一般情况下的, 回答如上: 就是: Yes,you must. No,you don't have to/needn't . 但是有一个特殊情况, 就是假如must在句中表达肯定的猜测推断的时候, 有例外, 这时候就要看句子暗含的时态. 例句: He must be in the classroom (now), isn't he? 他现在肯定是在教室, 不是么? He must have been to Beijing (last year), didn't he ? 他去年肯定是去过北京了, 不是么?
