问题 选择题

化学学习小组做实验时记录了下列实验现象,其中正确的是

A.细铁丝在氧气中剧烈燃烧,火星四射,有黑色固体生成

B.红磷在空气中燃烧,发出红色的火焰,产生大量白色烟雾

C.少量高锰酸钾固体溶于水可得到浅绿色溶液

D.分别点燃一小块棉纤维和羊毛纤维,都产生了烧焦羽毛的气味

答案

答案:A

红磷燃烧生成大量白烟,不是烟雾,故B错误,高锰酸钾溶于水是紫色的,故    C错误。点燃时,只有羊毛纤维能产生烧焦羽毛的气味。故D错误。

阅读理解

阅读理解。

     The other day, my friend Jane was invited to a 40th birthday party. The time printed on the invitation was

7:30 pm. Jane went off with her husband, expecting a merry evening of wine, food, and song.

     By 9:45, everybody was having great fun, but no food had appeared. Jane and David were restless. Other

guests began whispering that they, too, were starving. But no one wanted to leave, just in case some food was

about to appear. By 11:00, there was still no food, and everyone was completely off their heads. Jane and

David left hungry and angry.

     Their experience suggests that the words on the printed invitations need to be made clearer. Everyone reads

and understands the invitations differently. Most of us would agree that 6:30-8:30 pm means drinks only, go

out to dinner afterwards; 8:00 pm or 8:30 pm means possible dinner, but 9:30 pm and any time thereafter means no food, eat beforehand, roll up late.

     But this is not always the case. If asked to a students' party at 6:30 pm, it is unaccepted for guests to appear on time. Being the first to arrive-looking eager-is social death. When my mother is asked to a party at 6:30, she

likes to be there, if not on time, then no later than seven. My age group (late thirties) falls somewhere between

the two, but because we still think we're young, we're probably closer to student-time than grown-up time.

     The accepted custom at present is confusing, sometimes annoying, and it often means you may go home

hungry, but it does lend every party that precious element of surprise.

1. The underlined words "off their heads" probably mean ______.

A. tired

B. crazy

C. happy

D. encouraging

2. Jane and David's story is used to show that ______.

A. party invitations can be confusing

B. party-goers usually get hungry at parties

C. people should ask for food at parties

D. birthday parties for middle-aged people are dull

3. For some young people, arriving on time for a students' party will probably be considered ______.

A. very difficult

B. particularly thoughtful

C. friendly and polite

D. socially unacceptable

4. What is the general idea of the text?

A. It's safe to arrive late just when food is served.

B. It's wise to eat something before going to a party.

C. It's important to follow social rules of party-going.

D. There's no need to read invitations carefully.

名词解释