如图，在▱ABCD中，∠ODA=90°，AC=10cm，BD=6cm，则BC的长为（   ）

    Do you have lots of friends? What do you1friends and friendship? Are they very important for you? Some of your friends may have different views and interests, and some like doing the same2as you. Do you like friends different from3the same as you? You may like the friends who 4 the same interests as you. But I don’t really care.

   I have two good friends, Peter and James. Peter is 5me. I am a quiet boy, and Peter is also quiet. We6enjoy reading books and surfing the Internet. On weekends, we often go to the library or 7on the computer together. But James is very different from us. He likes playing ball games, and he is more athletic than us. He is 8more outgoing. He likes talking and often makes9laugh. You see, friends are not10to be the same. Do you agree with me?

下列各组反应中最终肯定不生成白色沉淀的是（　　）

将x⁴﹣2x²+1因式分解的最终结果是____ .

下列反应的离子方程式书写正确的是（   ）