问题 选择题

下列有机物存在顺反异构的是(   )

A.CH2=CH2

B. CH2Cl2

C. CH3CH=CHCH3

D. CH3CH2OH

答案

答案:C

题目分析:由于双键不能自由旋转引起的异构体,一般指烯烃的双键。顺反异构体产生的条件:⑴ 分子不能自由旋转;⑵ 双键上同一碳上不能有相同的基团。据此可知选项C中存在顺反异构体,答案选C。

点评:该题是高考中的常见考点和题型,属于中等难度试题的考查,试题基础性强,在注重对学生基础知识巩固与训练的同时,侧重对学生能力的培养和解题方法的指导与训练,旨在考查学生灵活运用基础知识解决实际问题的能力,有利于培养学生的逻辑推理能力和发散思维能力,提升学生的学科素养。该题的关键是明确顺反异构体的原理以及判断依据,然后结合题意灵活运用即可。

填空题
阅读理解

If the rose can be said to be a special flower, then the apple can be said to be a special fruit. It is very important in American culture. American stories speak of Johnny Appleseed, who went throughout America collecting apple seeds and planting apple trees. He had a great love for nature and went through fields and farms adding richness and beauty to the country.

One of the first sayings taught to school children is, "An apple a day keeps the doctor away." This short saying encourages children to eat fresh fruit to keep healthy. If someone always says good words to a person, people will call him an "apple polisher". This, however, is not a good name. If someone is very dear to us, we say that he or she is the "apple of our eye".

Most people believe that the fruit which Eve gave to Adam was an apple, even though the Bible(圣经) never says so. The apple, therefore, is a deep part of the language and stories of America.

An apple is also delicious. Apples can be cooked in many ways, used as a dessert (甜点) , and made into sweet juice.

In many parts of the country during the harvest season, a popular activity is to go into an apple garden to pick apples. Washington, D. C. and New York are both famous for their apples.

Finally, when it’s time to take a vacation to American cities, one can always visit New York, which is "the biggest apple" of all the American cities.

小题1:Why was Johnny Appleseed so famous?

A.He had a great love of nature.

B.He liked the American people.

C.He went throughout the country.

D.He collected apple seeds and planted apple trees.小题2:What does the underlined phrase "apple polisher" mean?

A.Something for cutting apples.

B.A person who likes to please others.

C.A person who is dealing with fruits.

D.A machine for cleaning apples quickly.小题3:Which of the following is TRUE with apples?

A.Apples are medicine.

B.Apples are the most important food.

C.New York is famous for its big apples.

D.The Bible says Adam was given an apple.小题4:The passage is mainly about______.

A.stories about the apple

B.apples in American culture

C.some famous sayings of the apple

D.big cities that is famous for apples