下列哪种情况不宜洗胃（） A.有机磷农药中毒 B.汽油中毒 C.硝酸盐中毒 D.安眠

小明和小花同学在进行完碱的性质实验后，发现所使用的氢氧化钠溶液一直没有盖上塞子，已放置在空气中一段时间．于是他们对该氢氧化钠溶液中的成分产生了怀疑．

[提出问题]氢氧化钠溶液是否变质？

依据所学知识，对该瓶氢氧化钠溶液的溶质成分作了如下猜想：

[猜想]

①溶质只含______；

②溶质只含Na₂CO₃；

③溶质含Na₂CO₃与NaOH．

[设计与实验]

实验Ⅰ小明同学取少量样品溶液，滴加酚酞试液，溶液变为红色．由此小明认为猜想①正确．你认为他的结论是否正确？______，理由是______．

实验Ⅱ小花同学想要设计实验来证明溶质中既含有Na₂CO₃又含有NaOH，请你帮助她完成．

实验步骤	实验现象	结论

[反思]氢氧化钠溶液应密封保存．

由于混凝土梁碱－集料反应导致梁体产生裂纹应及时处理。

阅读理解。

     We once had a poster competition in our fifth grade art class.

     "You could win prizes," our teacher told US as she wrote the poster information on the blackboard. She

passed out sheets of construction paper while continuing, "The first prize is ten dollars. You just have to

make sure that the words on the blackboard appear somewhere on your poster."

     We studied the board critically. Some of US looked with one eye and held up certain colors against the

blackboard, rocking the sheets to the fight or left while we conjured up our designs. Others twisted their hair

around their fingers or chewed their erasers while deep in thought. We had plans for that ten-dollar grand

prize, each and every one of US. I'm going to spend mine on candies, one hopeful would announce, while

another practiced looking serious, wise and rich.

     Everyone in the class made a poster. Some of us used parts of those fancy paper napkins, while others

used nothing but colored construction paper. Some of US used big designs, and some of us preferred to

gather our art tidily down in one comer of our poster and let the space draw the viewer's attention to it. Some

of US would wander past the good students' desks and then return to our own projects with a growing sense

of hopelessness. It was yet another grown-up trick of the soil they seemed especially fond of making all of

US believe we had a fair chance, and then always-always-rewarding the same old winners.

     I believe I drew a sailboat, but I can't say that with any certainty. I made it. I admired it. I determined it

to be the very best of all of the posters I had seen, and then I turned it in.

     Minutes passed.

     No one came along to give me the grand prize, and then someone distracted me, and I probably never

would have thought about that poster again.

     I was still sitting at my desk, thinking, what poster? When the teacher gave me an envelope with a ten-

dollar bill in it and everyone in the class applauded for me.

1. What was the teacher's requirement for the poster?

A. It must appear in time.

B. It must be done in class.

C. It must be done on a construction sheet.

D. It must include the words on the blackboard.

2. The underlined phrase in paragraph 3 most probably means _____.

A. formed an idea for

B. made an outline for

C. made some space for

D. chose some colors for

3. After the teacher's words,all the students in the class _____.

A. 1ooked very serious

B. thought they would be rich

C. began to think about their designs

D. began to play games

4. After seeing the good students' designs,some students _____.

A. 1oved their own designs more

B. thought they had a fair chance

C. put their own designs in a comer

D. thought they would not win the prize

5. We can infer from the passage that the author _____.

A. enjoyed grown-up tricks very much

B. 1oved poster competitions very much

C. felt surprised to win the competition

D. became wise and rich after the competition

棕榈科为重要的纤维植物，其纤维主要来自（）。

A.叶鞘

B.茎韧皮部

C.果皮

D.树皮

民航局具体实施民用机场航空器活动区道路交通安全的监督管理工作。（）