题目

常温下，取pH＝2的两种二元酸H2A与H2B各1 mL，分别加水稀释，测得pH变化与加水稀释倍数有如图所示关系，则下列有关叙述正确的是( ) A．H2A的电离方程式为H2A  H＋＋HA－，HA－      H＋＋A2 B．pH＝4的H2A水溶液中c(OH-)=10－12 mol·L－1 C．NaHA、NaHB的混合溶液中，阴离子有A2－、HA－、HB－、B2－、OH- D．Na2B的水溶液能与H2A溶液发生反应请根据下面提示,写一篇短文.词数不少于 50. In your English class, the teacher shows the picture below and asks the class to discuss it. Your classmates may have different understandings. Look at the picture carefully and tell the class how YOU understand it. 提示： 拔河(n.)  tug-of-war