This type of bamboo grows very fast and it will take only three to five years it can be u

问题补充：

This type of bamboo grows very fast and it will take only three to five years it can be used in various fields .

A. before

B. since

C. when

D. as

答案：

(答案→)A. before

B. since

C. when

D. as

解析：：考查固定句型。It be 一段时间 before从句。意为：一段时间以后某事才发生。句意：这种竹子长得很快。三到五年以后就可以在不同的领域被使用了。巩固A正确。