How long are they planning to stay there?(For)two weeks.
问题描述：
How long are they planning to stay there?(For)two weeks.
括号处为何用for?可以用on吗?求原因·~
答
在特定的某一天,用介词on,如 on Sunday
在特定的某个时点,用介词at.如 at 7:00
在某段时间,用介词in 或during,如 in winter,during July
一段时间,用介词for,如 for a month,for a year
所以,上面不能用on,只能用for