从结构层次看，可以把管理系统分为______、______、______。

根据句意，用所给动词的适当形式填空。

1. —Who will be the host of the party?

    —As far as I know, Linda has already _____ (choose).

2. I'm sorry _____ (keep) you _____ (wait) for so long.

3. Who would you like _____ _____ (thank) for your achievements?

4. He thought they _____ (not see) each other again.

5. Thank you very much for _____ (help) me with my English.

移植排斥反应损伤机制中能激活CTL、NK杀伤移植物，使B细胞产生抗体的细胞因子是（）

A.IL-1

B.IL-8

C.IL-2

D.IL-4

E.IL-5

书面表达。

某英文报社举办以"I Like Reading"为主题的征文活动,你打算投稿.请根据以下要点写一篇短文:.

      你为什么喜欢读书；请给出至少两个理由.

      你喜欢读哪一类的书(例如:历史、科学、文学等)?

请给出至少两个理由.

注意:短文开头已给出,并不计人总词数(100词左右).

                                                                   I Like Reading

Reading is my favorite hobby.                                                                                                

番泻叶中的番泻苷类有较强的泻下作用。

It is said that a new policy is being put( )practice in your foreign trade.

A．on

B．into

C．under

D．with