若水准仪的圆水准轴不与垂直轴平行,则用角螺旋使圆水准气泡居中,后旋转180度,将()。
A.圆水准气泡仍居中
B.水准气泡无变化
C.圆水准器的气泡偏离中心
D.都不对
参考答案:C
比较大小:38°15′______38.15度(填写“>”、“=”、“<”).
John has two brothers, but either ____ out of work now. [ ]
A. are
B. is
C. has
D. have