排气门关闭，进气门关闭，活塞上行。一定是（）
A、进气行程；
B、排气行程；
C、膨胀行程；
D、压缩行程
参考答案：D
In case of emergency, whether knowing how to apply first aid or not really ________ in matters
concerning wounds like swollen wrists, broken arms, burns, cuts, and so on. [ ]
A. makes difference
B. makes a difference
C. makes differences
D. makes different
索赔事件发生（）天内向工程师发出索赔意向通知
A.21
B.14
C.7
D.28
