play football   

已知H^＋(aq)＋OH^－(aq)===H₂O(l)　ΔH＝－57.3 kJ·mol^－1。以下四个化学反应方程式：
①H₂SO₄(aq)＋2NaOH(aq)===Na₂SO₄(aq)＋2H₂O(l)；
②H₂SO₄(aq)＋Ba(OH)₂(aq)===BaSO₄(s)＋2H₂O(l)；
③HCl(aq)＋NH₃·H₂O(aq)===NH₄Cl(aq)＋H₂O(l)；
④CH₃COOH(aq)＋NH₃·H₂O(aq)===CH₃COONH₄(aq)＋H₂O(l)，其中反应热为57.3 kJ·mol^－1的是(　　)

跳伞运动员从静止在空中的直升飞机上下落，在打开降落伞之前做自由落体运动，打开降落伞之后做匀速直线运动．则描述跳伞运动员的v﹣t图象是下图中的（　　）

在细胞质中与核膜、细胞膜具有结构联系的细胞器是(    )

根据短文内容，选择最佳答案。
B
    Hello! My name is Kate. This is my bag. It's a nice bag, right? It is from my mother.
    What's in my bag? A ruler is in it. And the ruler is white. It's not mine. It's Lily's. Lily is my sister. She likes white but I don't. Two pencils are in it, too. One is red and the other is blue. They are mine. Look, a nice watch is in it. The watch is white and blue. It's mine and it's from my father. A notebook is in my bag, too. The notebook is yellow and blue. Is this notebook mine? No, it's Anna's. Anna is my cousin. She likes yellow and blue very much.