【单选题】有关 Na 2 CO 3 和 NaHCO 3 性质的说法正确的是 ( )
A.
热稳定性: Na 2 CO 3 < NaHCO 3
B.
相同温度下,在水中的溶解度: Na 2 CO 3 < NaHCO 3
C.
Na 2 CO 3 溶液和 NaHCO 3 溶液可用氯化钡溶液鉴别
D.
NaHCO 3 溶液能与碱溶液反应而 Na 2 CO 3 溶液不能
【简答题】unit 1 page 7 passage
【单选题】Now children, turn to Page _____ and look at the _____ picture in Unit 1.
【单选题】UNIT 1 PAGE 10 PASSAGE 1.2
【单选题】UNIT 1 PAGE 10 PASSAGE 1.1
【单选题】What is the power source for arc welding?
【简答题】What is shielded metal arc welding?
【单选题】UNIT 1 PAGE 10 PASSAGE 1.3
【简答题】A: Could you introduce this welding equipment to me? B: Sure. The welding equipment is called a wire feeder . A: What are the main parts of it? B: The main parts of it are: handle , wire reel , wire d...
【单选题】What is the temperature in an electric arc welding?( )