水平角测量时，对任一方向盘左和盘右两次照准读数差，称之为2C值；竖直角测量时，对任一方向照准其盘左和盘右读数的差数之半，称为指标差。
参考答案：错
–Do you know __________ the Capital Museum? –Next Friday.
A．when will they visit
B．when they will visit
C．when did they visit
D．when they visited
书香城市（县级）标准指标体系要求东部地区职工书屋设置率不少于域内千人以上企业的40%。
