起吊活塞组件应(),以防超重()。
A.核算活塞组件的重量
B.核对绳索的许用荷重
C.检查吊钩重心与零件重心的一致性
D.以上均是
参考答案:D
Although there were only five athletes ____ in the race, it was a rather exciting one.
A.competing
B.having been competed
C.to compete
D.to be competed
下列叙述中正确的是
A.盐类物质一定含有金属阳离子
B.H2SO4的摩尔质量是98
C.凡能电离出H+的化合物均属于酸
D.等质量的CO与CO2中所含碳原子数之比为11︰7