Why did you decide on Beijing for vacation?为什么用介词on

Why did you decide to go to college? Why did you decide it so fast? why people like to think more ? Why did you decide on Beijing for vacation?为什么用介词on Why did you decide to be a biology major? 这句话怎么解释?major在句中的意思是什么? why did you miss Why did you leave why did not you why did you tdlk like Why did you leave me why did you say goodbye why did you let it why did you do it Why did you do it? 求改错:Why do you decide to Beijing for vacation? Please tell us why you decide _____(go) there. did you decide where ____(have) your vacation? why have you decided to choose our hotel?和why did you decide to choose our hotel 有区别么?用did是不是错了.还有帮我划出一下这个句子的成分you know when I wanted to be with you forever.尤其是when 后面的成分,want to be what did you decide ____ afterschool?1.to do 2.doing 3.did 4.do