——color is the tree?——处为什么用what而不用which?

what color is the tree 怎么回答? He is the man which he was.这里为什么不用who而用which呢, which is bigger,the sun or the earth?为什么用or而不用and? 为什么用which 不用what What color is your( t )?——It is black which/what is the best time in Shanghai?—Spring. what is the biggest animal on the earth 为什么不用which the man under the tree is Mr Li对under the tree提问,为什么用which,不 what class would you like to fly?中为什么用what而不用which what class would you like to fly 为什么用what而不用which>> what time does the shcool begin?为什么用does而不用is? The cat is in the tree?为什么不用on?