下列离子能在pH为13的水溶液中大量共存的是( )
A:K+、SO42-
B:Cu2+、NO3-
C:Cl-、H+
D:Ca2+、CO32-
“其制两柄上弯,高可三尺……其所盛种粒,各下通足窍,仍旁挟两辕,可容一牛,用一人牵,傍一人执耧,且行且摇,种乃自下。”这段话描述的农具出现于( )
分别说明上述措施对九寨沟旅游发展的意义。
Fire is very dangerous. It can ____people. We ____be careful with fire. We mustn't play near fires. We mustn't play with matches. We mustn't ____in the forest. When we see a fire, we must go outside ____,but ____use the lift.