水准仪应满足的主要条件是（）。
A.圆水准轴平行于纵轴
B.水准管轴平行于视准轴
C.横丝垂直于纵轴
D.横轴垂直于视准轴
参考答案：B
—Boy, you _______ lean (伸) out of the window while the bus is running. That’s dangerous.
—Sorry, I won’t do that again.
A．needn’t
B．oughtn’t
C．couldn’t
D．mustn’t
I bite my hairs. I must break （）.
A. the habit to me.
B. the habit with myself.
C. myself of the habit
D. of the habit myself
