下列单位中哪个是电量的单位（　　）

现有H₂SO₄和CuSO₄的混合溶液，为了测定CuSO₄的质量分数，某兴趣小组进行如下实验：取混合溶液于烧杯中，向其中加入铁片至完全反应。反应前后，有关数据如下。

    Mr. Brown lives on Green Street now. He wants to send a postcard(寄明信片) to his pen friend in Toronto, but he doesn't know where the post office is. “ where is the post office？” he asks his new neighbor Joe. “I want to send a postcard to Toronto.” “The post office is quite far from here，” answers Joe. “If you only want to post some letters(信件) or postcards, you needn't go to the post office. You can put them into a mailbox（信箱）down the street.”

我国许多大河滚滚东流，既沟通了东西交通，又产生了巨大水能，这是因为我国（　　）