用所给单词的正确形式填空。

1. —Can she______ ?

    —Yes, she ______ every day. (skate)

2. ______ is my favorite sport. I can ______ in the pool. (swim)

3. —Do you enjoy ______ sports?

    —Yes, I'm very good at ______ cartwheels. (do)

4. I can ______ . Now, you see, I am______ now. (ski)

5. ______ talking! The teacher is coming. He can do 100 pushups without______ .(stop)

皮下气泡是一种常见的连铸坯（）。

A、外部缺陷

B、内部缺陷

C、形状缺陷