Which one to choose?为什么要用to?

Which one to choose?为什么要用to? Which to choose/which one to choose which one to choose Which one to choose?Thanks. i really can't decide which one to choose为什么的which one to ch I do not know which one to choose.为什么是用不定式呢? which one you want to choose? Which one to choose?Why?Thanks. i don't know which one/which to choose选哪一个,为什么?再举例几个 I can not decide（ ） A.which one to choose B.to choose which I can't decide 是which one to choose 还是to choose which I decide which one to buy.为什么要用which one to buy?而不用which to