下列反应，其产物的颜色按红色、红褐色、淡黄色、蓝色顺序排列的是
①金属钠在纯氧中燃烧 ②FeSO4溶液中滴入NaOH溶液并在空气中放置一段时间
③FeCl3溶液中滴入KSCN溶液 ④无水硫酸铜放入医用酒精中
| A．②③①④ | B．③①②④ |
| C．③②①④ | D．①②③④ |
相关试题
Encourage your children to try new things, but try not to ___ them too hard.
| A．draw | B．strike | C．rush | D．push |
The computer was used in teaching. As a result, not only__________, but students became more interested in the lessons. 
| A．saved was teachers’ energy | B．was teachers’ energy saved |
C．teachers’ energy was saved | D．was saved teachers’ energy |
The children all turned ____ the famous actress as she entered the classroom. 
| A．looked at | B．to look at |
C．to looking at | D．look at |
Edward, you play so well. But I ______ you played the piano. 
| A．didn’t know | B．hadn’t known |
C．don’t know | D．haven’t known |
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