问题 选择题

已知维生素A的结构式可写为

,式中以线示键,线的交点与端点处代表碳原子,并用氢原子数补足四</PGN0006B.TXT/PGN>价,但C、H原子未标记出来。关于它的叙述正确的是             

A.维生素A的分子式为C19H30O

B.维生素A是一种易溶于水的醇

C.维生素A分子中有异戊二烯的碳链结构

D.1mol维生素A在催化剂作用下最多可与7molH2发生加成反应

答案

C </PGN0062A.TXT/PGN>

维生素A可以看作是一种醇,但由于碳原子数的增多,该有机物在水中溶解度下降。教材中提到乙酸与水互溶,而硬脂酸就不溶于水这就是证明。维生素A分子中含有5个C=C,所以1mol维生素A最多可以和5molH2发生加成反应。

说明:乙醇与水互溶,说明乙醇在水中的溶解度极大,但不能机械地认为醇在水中的溶解度一定很大,忽视了由于碳原子增多,烃基增大,憎水基团扩大,一定会影响整个醇在水中的溶解度。所以学会辩证地看同类物质物理性质、化学性质的递变。

阅读理解

Research has shown that music has an important effect on one’s body and psyche (心灵). In fact, there is a growing field of health care known as music therapy(治疗), which uses music to treat diseases. Even hospitals are beginning to use music therapy. This is not surprising, as music affects the body and mind in many powerful ways.

Research has shown that quick music can make a person feel more alert(警觉戒备), while slow music can produce a calm, deep thinking state. Also, research has found that music can change brainwave activity levels. This can help the brain to change speeds more easily on its own as needed, which means that music can bring lasting benefits to your state of mind, even after you’ve stopped listening.

Breathing and heart rates can also be influenced by music. This can mean slower breathing, slower heart rate. This is why music and music therapy can help reduce the damaging effects of long-term stress, greatly promoting (促进) not only relaxation, but health.

Music can also be used to bring about a more positive state of mind by helping to keep worries away. Music has also been found to bring many other benefits, such as lowering blood pressure and reducing the risk of strokes(中风). It is no surprise that so many people are considering music as an important tool to help the body become or stay healthy.

小题1:What can we infer about music therapy(治疗)?

A.It is a type of music.

B.It is a research about music.

C.It is a kind of musical effect on diseases.

D.It is the use of music method to help treat diseases.小题2:According to the second paragraph, we can know that ________.

A.music with different speeds has different effects

B.quick music is not good for one’s health

C.slow music can help one to think more calmly and slowly

D.music will have less benefit after one stops listening小题3:The reason why music can help deal with stress is that ________.

A.it is used by many hospitals

B.it can help change brainwaves

C.it does good to breathing and heart rates

D.it can bring a more positive state of mind小题4:According to the passage, music can help deal with all the following EXCEPT ______.

A.nervousness

B.mind illnesses

C.strokes

D.high blood pressure

多项选择题