冲刷作用形成()。
A. 残积土
B. 坡积土
C. 洪积土
D. 冲积土
The decibel(分贝)is one tenth of a bel, ______ named after Alexander Graham Bell.
A. a unit
B. is a unit
C. a unit is
D. a unit being
《环境空气质量标准》(GB3095-2012)中将空气功能区分为几类?
A. 二类
B. 三类
C. 四类
D. 五类
By an ohmmeter ______ the instrument used to measure resistance.
A. mean
B. means
C. is meant
D. are meant