钢筋的屈服强度是指（）。
A.比例极限
B.弹性极限
C.屈服上限
D.屈服下限
参考答案：D
________ the problem of land erosion(侵蚀) getting more serious, the government is searching for a way to deal with it.
A．As
B．When
C．With
D．If
多形红斑的特征性皮损是
A．风团样红斑
B．虹膜样红斑
C．鳞屑性红斑
D．环状红斑
E．地图状红斑
