题目

Mark Zuckerberg is the founder of the site Facebook, ______ you can have alook at each other's pictures. A . where B . which C . when D . as 答案：A下列电离方程式中，正确的是(    )       A   Na2SO4       ＝Na+＋SO4-2       B  Ba（OH）2   ＝Ba 2+  ＋ OH-2   C  Al2（SO4）3 ＝2Al3+＋3SO42-   D  Ca  (NO3）2  ＝ Ca2+＋ NO32-