问题 单项选择题 A1型题

水的化学耗氧量代表()

A.水体中可被氧化的有机物和还原性无机物的总量

B.水体中氧化物的含量

C.水体中可被氧化的有机物的总量

D.水体中可被氧化的无机物的总量

E.水体中氧化和还原性有机物的总量

答案

参考答案:A

解析:化学耗氧量亦称“化学需氧量”,简称“耗氧量”。用化学氧化剂(如高锰酸钾、重铬酸钾)氧化水中需氧污染物质时所消耗的氧气量,常以符号COD表示。计量单位为mg/L。是评定水质污染程度的重要综合指标之一。COD的数值越大,则水体污染越严重。

阅读理解

Beijing leading schools say “No” to students’ mobile phones.

Three reasons make some leading schools in Beijing discourage middle school students from bringing mobile phones to campus.

First, it is dangerous for children to bring valuable mobile phones along to school for it is possible for them to be lost during physical exercise and other activities and may cause unnecessary trouble to teachers.

Second, mobile phones are bad for students’ studies. Many teachers complain that some students have phone calls in class, disturbing themselves and others.

Third, mobile phones serve as a hotbed for students’ vanity(虚荣). A new Grade One senior high school student in a leading school asked his parents to buy a 4000-yuan colored-screen mobile phone, which turned out to be his fifth one ever since he entered the middle school.

Most headmasters and teachers in leading schools of Beijing thought that IC telephones on campus have made it very easy for students to get in touch with others, so middle school students should not bring mobile phones to school at present.

1. According to the passage, without mobile phones, how can the students get in touch with others?

A. By writing letters to each other.                       B. By sending e-mails.

C. By using IC telephones.                          D. By no means.

2. Which is NOT the reason that makes the schools say “No” to students’ mobile phones?

A. It is not safe for children to bring mobile phones to school.

B. It may give students a feeling of vanity.

C. It is bad for students’ studies.

D. Most headmasters and teachers don’t want students to bring mobile phones to campus.

3. Why did the new Grade One student ask to buy him the fifth mobile phone since he entered the school?

A. His family had a lot of money.

B. He wanted to show that his family was very rich.

C. His parents loved him too much.

D. The first four mobile phones were all lost.

4. What is the writer’s attitude towards students’ bringing cell phones to school?

A. negative.         B. acceptable.        C. not mentioned.     D. positive. 

单项选择题