后制动器的齿轮油应()更换一次。
A、20天
B、15天
C、30天
参考答案:A
Tom,together with Mary and Alice,______swim this afternoon.
A.is going to
B.are going to
C.was going to
D.were going to
发生行车事故的相关部门,应于事故后72小时内写出“行车事故报告”一式四份。