英语语法的问题,请帮我看看这几句有语法错误么,
4 Today people communicate by e-mail and sell phones but twenty-five years ago the only choice is letter.twenty-five years 前要加in么
5 As soon as he arriverd at the hotel,he taken a shower.中间的逗号要去掉么?
6 Dr.Weeks never sees students in the morning ,so he feels a bit depression.