【 it's time to 和 it's time for 】
——————这其实是一个句型,只不过后面要跟不同的东西.
——————It's time to跟的是不定式（to do）.也就是说,要跟一个动词,意思是“到做某事的时候了”.如：
It's time to go home.
It's time to tell him the truth.
——————It's time for 跟的是名词.也就是说,不能跟动词.如：
It's time for lunch.(没必要说It's time to have lunch)
It's time for class.(没必要说It's time to begin the class.)
【总之,句子能短则短.能省一个词就省一个词.用一个名词就解决的问题,就不用to 加动词了!】
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Is it time to eat our dinner
Is it time for us to eat dinner
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It's + for + 名词 ；
It's time + to + 动词词组 ；
It's time for supper.（该吃晚饭了） ＝ It's time to have supper.
It's time for class. ＝ It's time to have class.
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It's time to do sth．————到该做某事的时间了.
It's time for doing sth．————是做某事的时候了.
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The meaning is the same.In the first sentence,the verb "do" is an infinitive.In the second sentence,the verb "doing" is a gerund.In English,infinitives and gerunds are often interchangeable without changing the meaning of a sentence.Look at these two sentences for example:I like to swim.I like swimming.In the first sentence,"swim" is an infinitive.In the second sentence,"swimming" is a gerund.Being nonfinite verbs,both the gerund and infinitive act like nouns and have the same meaning.The meaning of both sentences is the same,just as in your two sentences.
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——————It's time for us to study hard.——————该是我们努力学习的时候了.（这是一个固定句型,记熟哦!）
It’s time for him to do homework.——————是他做作业的时间了.
it's time for me to do homework.——————这是我该做功课的时间了
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