下列哪一个是燃烧发生的必要条件:()。
A、可燃物
B、氧化物
C、引火源
D、以上都是
参考答案:D
无缝线路固定长度不得短于()。
A、50m
B、75m
C、100m
D、150m
—When will you be through with your work.Jones —()My boss usuallY finds something for me to do at the last minute.
A.Who knows
B.Would you help me
C.I beg your pardon
D.Anything the matter