某粗盐固体样品中含有少量 C a C l 2 、 M g C l 2 、 N a 2 S O 4 、 M g S O 4 和泥沙,进行以下操作可得到纯净的 N a C l 晶体:
①加过量的 N a O H 溶液;②加 H 2 O 溶解;③加过量的 B a C l 2 溶液;④过滤;⑤蒸发;⑥加过量的 N a 2 C O 3 溶液;⑦加适量的稀盐酸
则正确的操作顺序是( )
______ carefully,please! Look at the road sign.There is a school ahead.( )
A.DriveB.To driveC.Driving
There's ______ in the city.Why not have a picnic in the countryside?
Great! Daweishan Mountain might be a good choice.( )
A.interesting something
B.nothing interesting
C.anything interesting
______ April 22nd,people around the world celebrate Earth Day in different ways.( )
A.InB.AtC.On
Hello,John.This is Mike.What are you doing now?
I'm watching a football match.It started at 7:30 p.m.and ______ on for another one hour.( )
A.has beenB.wasC.will be
Boys and girls! I hope you can get good grades in this exam.
______, Miss Lu!( )
A.Thank youB.You are OKC.Good idea