Tom often spends as much time as he can to learn English.为什么

spend 主语是人
1.sb.spend……on sth.
2.sb.spend……(in) doing sth.
例如：He spent twenty yuan on the book.
he spent two hours (in) finishing the work
spend ...to do 没学过,在这 是表目的吧,感觉布太对 啊.