A. 升髙 B. 降低 C. 不会受到影响 D. 大幅度变化
A. 正确 B. 错误
A. excessive strain is placed on the shorter leg B. the shorter leg may fail C. the longer leg is slack D. All of the above
A. 机械伤害 B. 中毒 C. 触电 D. 着火