As we all know the functions of our skin are very .A. complexB. simpleC. briefD. tight

问题补充：

As we all know, the functions of our skin are very .

A. complex

B. simple

C. brief

D. tight

答案：

(答案→)A. complex

B. simple

C. brief

D. tight

解析：考查词义辨析，complex复杂的，simple简单的，brief简洁的，tight紧的，句意：众所周知，我们皮肤的功能非常复杂。故选A。