采用高压抗燃油的目的是防止()的事故发生。
参考答案:油系统漏油着火
— _______ did you go to Beijing?
— First I ______ the train to Tianjin, then I went to Beijing ______ bus. [ ]
A. When, take, by
B. How, took, on
C. When, take, on a
D. How, took, by
通常设备修理分为哪几个级别?