测量放线,当垫层混凝土的强度达到( )MPa以后开始放线,用经纬仪将水池的池壁、柱及进出水口的轴线投至垫层上(弹墨线)。
A.1.2B.1.1C.1.0D.0.9
参考答案:A
--- What did Lucy do yesterday afternoon?
--- She ____ her parents do the housework.
A.help
B.helped
C.will help
D.is helping
我国古代纪年方式有干支纪年,还有帝号纪年和年号纪年。( )