（－x＋y）（    ）=x²－y²，其中括号内的是（  ）

阅读短文，选择正确的答案。

    I am seven. I go to school every day. Classes start at eight o'clock. In the morning. I have Chinese, Art and Maths. I have English and P.E. in the afternoon. I get home at half past four. I watch TV at home. I have a good friend, Xiaotian. He sleeps at school. He goes to bed at nine. I go to bed at half past nine.

下列各组热化学方程式中，△H₁>△H₂的是
①C(s)＋O₂(g)===CO₂(g)     △H₁      C(s)＋1/2O₂(g)="==CO(g)     " △H₂
②S(s)＋O₂(g)===SO₂(g)     △H₁      S(g)＋O₂(g)===SO₂(g)        △H₂
③H₂(g)＋1/2O₂(g)===H₂O(l)  △H₁     2H₂(g)＋O₂(g)===2H₂O(l)     △H₂
④CaCO₃(s)===CaO(s)＋CO₂(g) △H₁     CaO(s)＋H₂O(l)===Ca(OH)₂(s)  △H₂

Writing stories and articles _____what I enjoy most，

下列各组书写完全正确的一组是（    ）