选择填空：
This area has been free from Foot-and-Mouth Disease ( ) two years.
A.for B.in C.after D.before
谢谢！

答案A，for
This area has been free from Foot-and-Mouth Disease for two years. 这地区摆脱口蹄病已经有两年了。

for＋一段时间，与现在完成时连用，表示到目前为止的一段时间。
如：I've known her for a long time. 我认识她已经很久了。

一段时间＋before，before的意思是“在那时以前”，与过去完成时连用。
如：When I went back to the school that I had left eight years before, everything was different. 当我回到八年前离开的这所学校时，一切都变样了。

另，before在用来表示“现在以前的任何时间”这意思时，与现在完成时连用。
如：I've never been here before. 我以前从未来过这儿。
Have you seen this film before? 你以前看过这部电影吗？