问题 选择题

如图所示装置,电流计的指针发生偏转,正极变粗,负极变细,符合这种情况的是

A.正极Cu,负极Al,S为浓HNO3

B.正极Ag,负极Fe,S为CuSO4

C.正极Al,负极Cu,S为浓HNO3

D.正极Zn,负极Cu,S为CuSO4

答案

答案:B

在原电池中较活泼的金属作负极,失去电子,发生氧化反应。电子经导线传递到正极上,所以溶液中的阳离子向正极移动,阴离子向负极移动。正极得到电子,发生还原反应。由于在该装置中正极变粗,负极变细,这说明溶液中金属阳离子在正极得到电子而析出,所以只有选项B是正确的,其余选项都是错误的,答案选B。

完形填空

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项.

Taking good notes is a time-saving skill that will help you to become a better student in several ways 1  Second, your notes are excellent materials to refer to when you are studying for a test. Third, note-taking offers variety to your study time and helps you to hold your interest.

You will want to take notes during classroom discussions and while reading a textbook or doing research for a report.2 Whenever or however you take notes, keep in mind that note-taking is a selective process.3

The following methods may work best for you.

●Read the text quickly to find the main facts and ideas in it.

●Carefully read the text and watch for words that can show main points and supporting facts.

● Write your notes in your own words.

● 4

● Note any questions or ideas you may have about what was said or written.

As you take notes, you may want to use your own shorthand(速记). When you do, be sure that you understand your symbols and that you use them all the time.5

A.Use words, not complete sentences.

B.There are three practical note-taking methods.

C.You must write your notes on separate paper.

D.Otherwise, you may not be able to read your notes later.E. you will also want to develop your own method for taking notes.

F. That means you must first decide what is important enough to include in your notes.

G. First, the simple act of writing something down makes it easier for you to understand and remember it.

填空题