(1)best前加the
(2)what改为how
(3)by改为in
(4)such改为so
(5)small前加a
(6)去掉to
(7)was改为is
(8)even去掉
(9)quick改为quickly
修改后文章变为：l want to know which is （the) best way to learn a language.l think we should remember (how) we all learnt our own language when we were children at school .if we could learn a second language (in) the same way,it would not seem (so) difficult as we expected .think of what (a) small child does every day.he listens to people close to him () speak and tries to learn something.he is using the language.he (is) talking with them in it and thinking in it all the time .()if people had to use a second language all the time,they would learn it (quickly).