应该用in the week还是for a week?

是in the week还是of the week,是in a week还是of a week for a week,once a week,in a week,after a week有什么区别 ____ in the mountains for a week,the student were The Smiths _______(leave) for China in a week. for a week 和in a week的区别 是on the first week还是in the first week in the week和in a week有什么区别? we have three classes ___PE every week.A.in B.for C.on 应该选择那 we have classes from Monday to Friday in a week 是in还是for 我今天 on last week还是in last week on the week与 in the week Sunday is the day in a week.