hadn't為什么，能解釋么不是hadn't,是hadhis sister had a bad cough,she?為什么是didn'this sister had a bad cough,she?為什么是didn't剛才那倒正確答案是hadn't你能幫我解釋一下兩道題的區(qū)別么had better是不得不的意思，那么遵循反意疑問句的前否后肯原則那跟下面一道有什么區(qū)別his sister had a bad cough,she?為什么是didn't嗯為什么had在此處做實義動詞，那么就要借助動詞do，因為句子的時態(tài)是過去式，所以就是did，則遵循前否后肯原則就有didn't嗯，謝謝呵呵給個好評吧