如图所示装置中，X是铁，Y是石墨电极，a是硫酸钠溶液，实验开始前，在U形管的两边同时各滴入几滴酚酞试液，下列叙述正确的是（ ）
| A．闭合K1，断开K2，X极放出H2 |
| B．闭合K1，断开K2，Y极为阳极 |
| C．闭合K2，断开K1，Y极的电极反应式为：O2＋2H2O＋4e－===4OH－ |
| D．闭合K2，断开K1，工作一段时间后，X电极附近显红色 |
相关试题
My friend showed me round the town, ______ was very kind of him. 
| A．which | B．that | C．where | D．it |
They use computers to keep the traffic _______ smoothly.
| A．being run | B．run | C．to run | D．running |
If you leave the club, you will not be_____back in .
| A．received | B．admitted | C．turned | D．moved |
What I need is_____ book that contains ______ABC of oil painting.
| A．a; 不填 | B．the; 不填 | C．the; an | D．a ; the |
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