一氧化碳浓度在()时,连续工作时间不得超过15~20min。
A.100mg/m3
B.150mg/m3
C.200mg/m3
参考答案:C
Every time Gina catches her employees ____________ time, she reminds them that time is money.
A.to waste
B.wasting
C.wasted
D.waste
课税会使纳税人()储蓄。
A.增加
B.减少
C.维持不变
D.相对增加