经纬仪对中是（）；整平是使仪器竖轴铅直和水平度盘水平。
A.圆气泡居中
B.使仪器中心与测站点安置在同一铅垂线上
C.视准轴水平
D.横轴水平
参考答案：B
It is often _____ that human beings are naturally equipped tospeak. [ ]
A. said
B. to say
C. saying
D. being said
煤气流速及压力各是多少，怎样影响洗苯的？
