鲨鱼是世界上唯一不患癌症的动物，研究发现其体内含有的角鲨烯（化学式为C30H50

—Is your friend quiet?

—No, he never stops       .

A．talk

B．talking

C．to talk

D．is talking

管理单元是提供高阶通道层和复用段层间适配功能的信息结构，它由（）和（）组成。

欲比较两地食管癌死亡率时，对两个率（）。

A.不需标准化，可直接进行比较

B.要考虑性别构成的影响，不必考虑性别构成的影响

C.要考虑年龄构成的影响，不必考虑性别构成的影响

D.不必考虑年龄、性别构成的影响

E.要同时考虑年龄、性别构成的影响

请先阅读李雷给王老师的来信，然后帮助王老师给李雷回信。

Dear Miss Wang,

I live in a boarding school and I go home every weekend. But when I came back to school this Monday, I found my wallet with all my money and identity cards had been stolen. I haven’t told my parents because they will be angry. Now I have to borrow money from my classmates .I’m so sad that I cannot concentrate (集中注意力) on my studies. Can you help me?

Yours,

Li Lei

注意：1. 给李雷至少两条建议；

2. 开头和结尾已经给出，不计入总词数；

3. 词数为80词左右。

Dear Li Lei,

I am really sorry that you lost your wallet.______________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

I hope you will find these ideas useful.

Yours,

Miss Wang

潜孔钻头按结构形式可分为（）大类。

A.二

B.三

C.四

D.五