题目

①Amy: Bye, Lucy. I have to bounce!Lucy: What?Amy: I have to bounce. You know—I have to go. We say that a lot in San Francisco.②Lucy: That's cool! What other things do you and your friends say?Amy: Well, for example, we say someone is 'sketchy' if we think they aren't very nice.Lucy: Sketchy? All right I like it.③Amy: What about things you say here in Britain?Lucy: Well, if I say ‘He's tasty’, do you know what it means?Amy: Beats me!Lucy: It means he's good-looking.④Amy: Look, there's Dave. He's quite tasty, isn't he?Lucy: Well, he's a bit sketchy sometimes—but I like him!Dave: 有A、B、C、D四种无色气体，①A能使湿润的红色石蕊试纸变蓝；②一定条件下，A可以与B反应生成C，C遇空气变为红棕色；③D与A混合生成白烟；④D的浓溶液与软锰矿（主要成分是MnO2）在加热条件下反应可制取黄绿色气体E；按要求回答下列问题：（1）写出②化学方程式______；（2）写出④的离子方程式______；（3）气体E有毒，实验室一般用______吸收，该反应的离子方程式是______．