we should spend as much time as we can to improve our englis

we should spend as much time as we can to improve our english.这个句子的疑问
we should spend as much time as we can to improve our english.曾经做过这样一道题,spend 是要你填空的地方,我想spend 后面不能跟to所以填了pay,求这里句子的语法用法.

你先看一个例句：
Mr.Huang told us to spend as much time as possible ________ our English.
A.to improve B.improving
应该选A.我理解spend time doing 意思就是do这个动作延续了多长时间,这里improve是一个结果.所以要用to improve 表目的
你的这个句子和例句是一个道理.