用所给单词的正确形式填空。

1. What are you ____________ (do)?

2. Lily is ____________ (swim) now.

3. Lily often ____________ (get) up early.

4. I like ____________ (pear).

5. I go to school ____________ foot.

6. My parents ____________ (be) teachers.

7. Mike is ____________ (read) a book.

8. My birthday is May ____________ (3).

循环链表的主要优点是 ( )

A．不再需要头指针了

B．从表中任一结点出发都能访问到整个链表

C．在进行插入、删除运算时，能更好的保证链表不断开

D．已知某个结点的位置后，能够容易的找到它的直接前件