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?