强度
参考答案：
金属材料在外力作用下抵抗变形和断裂的能力。
The teacher couldn't make himself ___ attention to because the students were so noisy. [ ]
A. to pay
B. to be paid
C. paid
D. pay
（）是运营过程中发生但不能直接计入个成本计算对象的费用。
A.人员费用支出
B.办公费
C.管理费
D.折旧费
