遇到下面情景，你会怎么说？选择正确的选项。

1. 对方问你的身体状况时，你应该说：[ ]

A. How are you?

B. What's your name?

C. Fine, thanks.

2. 当老师说“Sit down, please!”时，你应该说：[ ]

A. Great!

B. OK!

C. Thank you.

3. 早上见面时说：[ ]

A. Hello!

B. Good morning.

C. Goodbye.

4. 当你向别人介绍你的朋友王红时，你应该说：[ ]

A. This is Wang Hong.

B. She is Wang Hong.

C. Thank you, Wang Hong.

5. 当你问某物是什么颜色时，你应该说：[ ]

A. What colour is it?

B. I like red.

C. Is what colour?

具有趋化作用的补体成分是：（）

A.C3a

B.C3b

C.C4a

D.C5a

E.C2a