在处理燃气紧急事件时，以下哪一项为最优先的考虑？
A.保障生命
B.保障财产
C.找出及修理燃气泄漏
参考答案：A
—Do you know our city at all?
—Yes, quite well, this is the fourth time I _____ here. [ ]
A. had been
B. have been
C. was
D. am
试述减速器的日常检查检查方法。
