I was ashamed ______ lied to my mother. [ ]
A. to be
B. of having
C. that
D. of being
答案:B
用微孔滤膜采集金属颗粒物的优点是()
A.阻力小
B.滤膜可以反复使用
C.吸湿性不强
D.机械强度好
E.对颗粒物收集效率高
地基分为哪两类?一般建筑物选择哪一种地基?