金属结构主要受力构件因产生（）变形，使工作机构不能正常地安全工作时，如不能修复应报废。
A.弹性
B.塑性
C.刚性
参考答案：B
—Does your brother serve in the army?
—No, not now. But he _____ in the army for 8 years.[ ]
A. would serve
B. was serving
C. had served
D. served
白头翁治疗热毒血痢，是取其什么功效（）
A.清热燥湿
B.止血
C.清热解毒
D.利湿浊
E.凉血止痢
