一块长30厘米,宽15厘米,厚13厘米的长方体石料,加工后长宽高各减少5厘米,求去掉原料的体积。
30×15×13-(30-2)×(15-5)×(13-5)=3850(立方厘米)
According to some scientists, the computer will do much harm to people''s health as smoking and drugs do.
A.does much harm ... smoking
B.will do as much harm ... cigarettes
C.will be doing as much harm ... smoking
D.does as much harm ... cigarettes
曝气生物滤池是( )。
A.(A) 生物膜系统
B.(B) 活性污泥与生物膜混合系统
C.(C) 需污泥回流
D.(D) 适合处理污泥