We must take measures to protect endangered wildlife it is too late.A. now thatB. as long

问题补充：

We must take measures to protect endangered wildlife it is too late.

A. now that

B. as long as

C. unless

D. before

答案：

A. now that

B. as long as

C. unless

(答案→)D. before

解析：本题易误选C。后空意思“趁不太晚的时候”，before符合句意。