水准测量前后视距相等可消除:();(),大气折光差。
参考答案:仪器i角误差,地球曲率差
— Don't worry. Your father is coming to help you.
— _____ he doesn't come? [ ]
A. What about
B. Why not
C. What if
D. What for
简述外资并购的正面效应。