问题 单项选择题

下列各种说法中正确的是()。

A.取向力仅存在于极性分子之间

B.凡分子中含有H原子的物质一定有氢键

C.非极性分子中的化学键总是非极性键

D.色散力仅存在于非极性分子

答案

参考答案:A

解析:非极性分子之间只存在色散力,极性分子与非极性分子之间有色散力和诱导力,极性分子之间有色散力、诱导力及取向力。当H与电负性大,半径小的原子(F、O、N)形成分子时,分子之间才存在氢键。非极性键形成的分子是非极性分子,但极性键形成的分子如果分子结构对称,也是非极性的。

选择题
阅读理解

阅读理解。

     We have two daughters: Kristen is seven years old and Kelly is four. Last Sunday evening, we invited

some people home for dinner. I dressed them nicely for the party, and told them that their job was to join

Mommy in answering the door when the bell rang. Mommy would introduce them to the guests, and then

they would take the guests'coats upstairs and put them on the bed in the second bedroom.

     The guests arrived. I introduced my two daughters to each of them. The adults were nice and kind and

said how lucky we were to have such good kids.

     Each of the guests made a particular fuss over Kelly, the younger one, admiring her dress, her hair and

her smile. They said she was a remarkable girl to be carrying coats upstairs at her age.

     I thought to myself that we adults usually make a big "to do" over the younger one because she's the one

who seems more easily hurt. We do it with the best of intentions.

     But we seldom think of how it might affect the other child. I was a little worried that Kristen would feel

she was being outshined. I was about to serve dinner when I realized that she had been missing for twenty

minutes. I ran upstairs and found her in the bedroom, crying.

     I said, "What are you doing, my dear?"

     She turned to me with a sad expression and said,"Mommy, why don't people like me the way they like

my sister? Is it because I'm not pretty? Is that why they don't say nice things about me as much?"

     I tried to explain to her, kissing and hugging her to make her feel better.

     Now, whenever I visit a friend's home, I make it a point to speak to the elder child first.

1. What did the parents ask the sisters to do to welcome the guests?

A. To introduce themselves to the guests

B. To put away the guests' coats in another upstairs room.

C. To take off the guests' coats politely.

D. To entertain the guests with candies.

2. The underlined expression' make a big "to do" over' (paragraph 4) means ______.

A. show much concern about

B. have a special effect on

C. list jobs to be done for

D. do good things for

3. The guests praised Kelly for carrying coats upstairs because of her ______.

A. beautiful hair

B. pretty clothes

C. lovely smile

D. young age

4. Kristen felt sad and cried because ______.

A. the guest gave her more coats to carry

B. she didn't look as pretty as Kelly

C. the guests praised her sister more than her

D. her mother didn't introduce her to the guests

5. We can conclude from the passage that ______.

A. parents should pay more attention to the elder children

B. the younger children are usually more easily hurt

C. people usually like the younger children more

D. adults should treat children equally