一. It用作代词 1.it用作人称代词,代替前文提到的事物。 My pen is missing. I can’t find it anywhere. 2. 用以代替指示代词this,that. A:Whose umbrella is that? B:It’s Mary’s. A:What’s this? B:It’s a tulip.(郁金香) 3.也可以指动物或婴儿(未知性别的婴儿或孩子): Is this your dog?No, it isn’t.