在水平角测量中,用正镜和倒镜观测同一个角,其平均值则可以消除()。
(A)指标差;
(B)系统误差;
(C)偶然误差;
(D)视准轴、横轴误差。
参考答案:D
以宋室南渡为界,词作的情感和风格呈现出两种不同面貌的作家是:( )
A.辛弃疾
B.李清照
C.柳永
D.苏轼
It's reported that a plane with five people()crashed into the mountain several days ago.
A. on board
B. on the board
C. in board
D. in the board