吊钩做负荷试验，其开口度在没有任何显著的缺陷和变形下，不应超过( )。
A．0.25%
B．0.5%
C．0.7%
D．1.0%
参考答案：A
It was over a decade _______ they paid off all their debt. You can imagine what a hard life they had.[ ]
A. before
B. until
C. after
D. while
吊车作业完毕，室内行吊吊钩是否升至到接近限位器的高度？为什么？
