效应器官
参考答案：
污染物作用于靶器官后，其毒性作用直接由靶器官表现出来，则此靶器官为效应器官。
— Look! Mr Hu is on the other side of the stree.
— It ______ be him. He has gone to England. [ ]
A. mustn't
B. can't
C. shouldn't
D. won't
对于没有明显屈服点的钢材，通常以残余变形的（）的应力作为屈服强度。
A.20%
B.2%
C.0.2%
D.0.02%
