汽车队、警勤分队车辆全年行驶（）万公里以上无等级事故，可视情给主官干部嘉奖一次。
A.30
B.20
C.40
D.50
参考答案：A
There ______ snow in Canada every year. [ ]
A. has many
B. has much
C. are many
D. is much
土壤空气与大气在组成上有什么差异，为什么会产生这种差异？
