安装室内燃气表时,使之与灶具的水平投影间距不得小于()厘米
A、10
B、20
C、30
D、40
参考答案:C
People working 10 or 11 hours a day are more likely to suffer from health problems than _____who go off duty after eight hours.
A.those
B.that
C.these
D.them
混流泵的比转数一般在( )之间。
A.300~600
B.200~500
C.300~500
D.300~700