福岛核电站使用阻水材料“水玻璃”进行作业后,2号机组高放射性污水已停止泄漏。“水玻璃”的化学式为Na2SiO3,其中硅元素的化合价为[ ]
A.+2
B.+4
C.+6
D.0
答案:B
.
_____ you have a complaint to make, do something about it right away. The longer you wait, the harder it will be to get your complaint resolved.
A.If
B.Unless
C.Though
D.Since
能力差异的应用原则是什么?