Take a boat trip和Have a good time为什么不用变成动词不定式或动名词就可以直接在句首

Take a boat trip和Have a good time为什么不用变成动词不定式或动名词就可以直接在句首 It is a good time后面接动词原形,不定式,动名词,还是动词过去式? have a good time doing后面接分词短语作定语,为什么不能接动词不定式? Have a good time,Tom把Have a good time变成同义句 动词作主语要变成动名词,或是动词不定式.什么时候可以和动词不定式互换,什么时候不能换? It is time to have lunch 为什么be后面不跟动名词而更动词不定式 I hope you have a good time on the trip.(改为同义句) I hope you__ have enough time后跟动名词还是动词不定式 a cooker must have a good sens of smell为什么have不用变成has呢? have a good time动词怎么接? have a good time+动词什么形式 do you have a good time last trip?改错