为什么这里用is?

为什么这里用is? stealla is here.为什么这里用is? She is very young.这里为什么要用is what is she doing这里为什么用is? he is got the flu这里为什么要用is the new is very surprising这里为什么用surprising为什么? ____ you Peter?这里为什么要用Are?_____she Jane?这里为什么用Is？ whose bag is this 为什么这里用whose it is time for class.这里为什么用for? food is produced quite differently 为什么这里用 produced? it is really cold today为什么这里用really Playing sports is good for us 这里为什么用playing the cup is broken.这里为什么用过去分词? 为什么这里用 what ：Nine is to three what three is to one.Nine is to three what three is to one.,为什么这里用what? what is your job? is不是只用于三单吗? 为什么用在your这里 这里能用are吗 the house is of stone 为什么用is房子是石头建造的,为什么这里用 is 不用 建造 Here is an apple for you.这里为什么要用is 哪一个是你 Which one is you?这里为什么不用are而用is?