The National Day is coming , we'll have 7 days ______. [ ]
A. on
B. off
C. up
D. down
答案:B
在水准测量中,若后视点读数小于前视点读数,则()
A.后视点比前视点低
B.后视点比前视点高
C.后视点、前视点等高
D.后视点、前视点的高程取决于仪器高度