题目

阅读下面短文，从短文后所给的五个选项中选出能填入短文空白处的最佳选项，使短文通顺、连贯、意思完整。There are some skills for students to listen to the teacher in class, which means you're going to have to practice it. Just as you would have to practice basketball to be a better player, you also have to practice listening. How to listen in school? 【1】One of the things you need to do is to make sure that your mind doesn't wander (漫游). It's easy to start thinking about other things, especially when you' re not interested in the subject. 【29．常温下，向pH=8.4的Na2C2O4溶液中滴加0.1mol/L的HCl溶液，溶液pH与pOH[pOH=-lgc（OH-）]的变化关系如图所示，下列各点所示溶液中微粒的物质的量浓度关系一定正确的是（　　）A．a点：c（H+）+c（HC2O4-）+2c（H2C2O4）=c（OH-）B．b点：c（Cl-）＞c（H2C2O4）+c（HC2O4-）+c（C2O42-）C．c点：c（Na+）=c（HC2O4-）+c（C2O42-）+c（Cl-）D．d点：c（OH-）+c（Cl-）＞c（H+）+2c（H2C2O4）