动词不定式有没有过去式?假如这句话的谓语动词是过去式,动词不定式用什么时态?

动词不定式没有时态的变化.举个例子吧,比如：He wants to be a doctor when he grows up.变为过去时：He wanted to be a doctor when he grew up.这里的时态变化只是体现在谓语动词上,即wants变为wanted,而to be a d...