It's time for us to have dinner为什么是to have

It's time for us to have dinner为什么是to have
It's time for us to have dinner为什么是to have

It's time for us to have dinner为什么是to have
It's time for sb to do sth.
是该某人去做某事的时候了

time的定语

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你的问题本来就有问题。
It's time for sb. to do sth.(这是句式)
to have dinner(have是动词，动词前加to，短语，吃饭的意思，不定式)
所以,以上组合成It's time for us to have dinner

it's time for sb to do sth
是固定的搭配
意思是：是sb做sth的时间了。