按润滑剂的（）润滑系统可分为分散润滑、集中润滑。A.密度 B.粘度 C.形态 D.使

若数列{a_n}的前n项和S=n²-10n(n=1，2，3，…)，则此数列的通项公式为（    ）。

阅读下面短文，完成有关任务。

Reading is a good habit, but the problem is, there's too much to read these days, and too little time to read every word of it. (83) There are hundreds of skills to help you read more in less time. Here are two skills that I think are especially good.

Preview--if it's long and hard. Previewing is especially useful for getting a general idea of heavy reading like long magazine articles and business reports.

Here's how to preview.

●Read the first two paragraphs and the last two paragraphs carefully.

●Then read only the first sentence of the other paragraphs.

Previewing doesn't give you all the details. (84) It keeps you from spending time on things you don't really want--or need--to read.

Skim--if it's short and simple. Skimming is a good way to get a general idea of light reading --like popular magazines or the sports and entertainment of your daily paper.

Here's how to skim.

●Get your eyes to move fast. Sweep them across each line.

●Pick up only a few key words in each line.

Everybody skims differently. You and I may not pick up the same words when we skim the same piece, but we'll get a similar idea of what it's all about.

A. 根据短文内容简要回答问题。

小题1:How many skills are recommended in this passage?

____________________________________________

小题2:What should we do when we read sports news in a daily paper according to the passage?

____________________________________________

B．将短文中划线的两个句子译成汉语。

小题3:_________________________________________

小题4:________________________________________

C． 请给短文拟一个适当的标题。

小题5:_________________________________________

国际环境法萌芽时期是（19世纪中叶到（））。

公安机关的人民警察因履行职责的紧急需要，经出示相应证件，可以优先乘坐公共交通工具，遇交通阻碍时，优先通行。( )

在下列两个案例中各有5个问题，请在各问题答案的选项中，选出一个或一个以上正确答案。

质量出现问题的产品退运时，应当办理的海关手续有( )。

A．应当填写出口货物报关单进行申报

B．提供原货物进口时的进口货物报关单

C．已经征收进口税的，自缴纳税款之日起1年内可以退还

D．自进口1年内原状退货复运出境，经海关核实免征出口税