生态影响一级评价，成图范围是50km2，成图比例尺应该大于等于( )。 A．1:1

电流的大小和方向随时间按一定规律变化，即由小变大，又由大变小，一段时间为正，一段时间又变为负（正负变化即表示其方向的变化），这种电流叫做（）。

(各备选选项中，至少有一项符合题意。)

大气环境影响预测项目选择( )。

A．臭气、H₂S、NH₃

B．TSP、SO₂、NO₂

C．臭气、H₂S、NH₃、TSP、SO₂、NO₂

D．二噁英

Recently in the hope of earning both money and social experience, I became a door-trw door salesman.

I once read a saying. “If somebody wants something of yours, you will be treated as warmly as spring, but if they don’t you may be treated as coldly as winter.” You may consider this an exaggeration (夸张), but if you are a salesman, it is clearly correct.

You would never have found it to be so true if you hadn’t been a salesman. You needn’t stand doubtful looks and unfriendly comments; you needn’t listen to something completely wrong and nod to say that it was quite right, you needn’t worry about being refused time after time; you needn’t always keep patience and a smile; you needn’t repeat the same sentences over and over again; you needn’t talk to somebody you dislike ....

I did this work for a month, then I decided to give it up; Apart from the reasons above, I found I was paying too much attention to the job and thus sacrificing my study time. The latest test result proved that my grades were getting worse.

Even worse, I hadn’t enough time to join my classmates in college activities. Some times 1 felt lonely and unhappy because of both my study and my part-time job. Now I don’t think it is worth doing such a thing for even though I was earning money it came at great cost.

Newspapers and magazines often publish stories about excellent students who do part-time work while also keeping high scores in class. But according to my experience, park-time work can have some strong negative influences on study.

Most students don’t view the relationship between study and work correctly. In my opinion, if it isn’t a must for financial reasons, students should be careful about taking up a part-time job.

小题1: From the text, we can tell that the writer is _____.    

A．an unemployed man

B．a middle-school student

C．a college student

D．a door-to-door salesman小题2:Which of the following words has the closest meaning to the underlined word “sacrificing”? 

A．Losing

B．Wasting

C．Using

D．Getting小题3:The writer thought_____. 

A．doing a part-time job was unnecessary

B．part-time jobs had good effect upon study

C．it was hard to deal with the relationship between study and work

D．part-time jobs would be good for every college student小题4:What would be the best title for the text _____.

A．Part-time Jobs Are Useful

B．Part-time Jobs Can Cost Dear

C．Students Shouldn’t Take Part-time Jobs

D．Part-time Jobs Are Important to Many Students

货币政策的主要内容是什么？

藻类中发现的叶绿素通常集中在称作（）的细胞质的小体中。

A.核糖体

B.线粒体

C.叶绿体

D.溶酶体