What does his father want _________?[ ]
A. know
B. to know
C. knows
D. knowing
答案:B
铝在氧气中燃烧生成氧化铝.在这个反应中,铝、氧气、氧化铝的质量比是 [ ]
A.27:32:102
B.27:24:43
C.4:3:2
D.108:96:204
铺设室外给水管道时,金属管道的覆土深度一般不小于______m。
A.0.1
B.0.5
C.0.7
D.1.0