圆柱齿轮的齿形没有（）。
A、直齿
B、斜齿
C、人字齿
D、矩形齿
参考答案：D
-I have missed a chance to go to Beijing University.
-________[ ]
A.You're lucky.
B.What a pity!
C.Congratulations!
D.I'm sorry.
简述电喷发动机怠速不稳故障的判断和排了作。
