如图,在电线杆上的C处引拉线CE、CF固定电线杆,拉线CE和地面成60°角,在离电线杆6米的B处安置测角仪,在A处测得电线杆上C处的仰角为30°,已知测角仪高AB为1.5米,求拉线CE的长(结果保留根号).
3000000平方米=____公顷=____平方千米
— I haven't got the reference book yet, but I'll have a test on the subject next month.
— Don't worry. You _______ have it by Friday.
下列设备应用到的物理知识解释错误的是( )