酸雨通常是指表示酸碱度指数的 pH 值低于()的酸性降水
A. 4.6
B. 5.6
C. 6.6
D. 7
由计算器算得(2.236×1.1124)÷(1.036×0.200)的结果为12.004471,按有效数字运算规则应将结果修约为()
A. 12.0
B. 12.00
C. 12.004
D. 12
Which of the following commands is used to view the current process of the system()
A. rm
B. touch
C. mkdir
D. ps
介观世界的尺寸范围1 nm到()nm
A. 10
B. 100
C. 10000
D. 100000