柱塞直径为9毫米,头部圆柱面上切有50°右旋()
A、横槽
B、斜槽
C、直槽
D、竖槽
参考答案:B
Though he has studied ____ at Russian for ten years,he can still _____speak the language.
A.hard,hard.
B.hardly,hardly.
C.hard,hardly
D.hardly,hard
Everything all right. Let's a good rest.[ ]
A. are, have
B. are , has
C. is, have
D. is, has