is的否定式为isn't,那么,are和am的否定式是否为aren't和amn't呢

is的否定式为isn't,那么,are和am的否定式是否为aren't和amn't呢 must的否定式是musn't还是mustn't have to的否定式是不是don't.have.to a祈使句的否定式可说成Don't be . 一般现在时的否定式和疑问式： 为什么must的否定式要用can’t或者needn’t?may要用can’t will的否定式`` will的否定式 为什么must be的否定式是can't be而不是mustn't be he is mr zhang的否定式 used to do 的否定式didn't use to do 中的use怎么读? should have done 它的否定式是 shouldn't have done