我们知道许多“化学之最”，比如地壳中含量最多的元素是（ ）
A．O
B．Al
C．N
D．Si
答案：A
A U.N. peace-keeping _______ was sent to that country and the soldiers would devote all their _______ to their job.
A．power; energy
B．power; strength
C．force; energy
D．force; strength
铸造蜡要求流动变形率为（）
A．小于0.5%
B．小于1%
C．大于0.5%
D．大于1%
E．小于0.1%
