食品保鲜的措施有添加防腐剂.充填气体.放置干燥剂和脱氧剂等.(1)丙酸钠是一种常用的防腐剂.其化学式为C3H5O2Na.它由种元素组成.碳元素和氧元素的质量比为 .(2)生石灰是常用的干燥剂.——青夏教育精英家教网—

（6分）食品保鲜的措施有添加防腐剂、充填气体、放置干燥剂和脱氧剂等。
（1）丙酸钠是一种常用的防腐剂，其化学式为C₃H₅O₂Na。它由     种元素组成，碳元素和氧元素的质量比为    。
（2）生石灰是常用的干燥剂。请用化学方程式表示其作干燥剂的原因      。
（3）铁粉也可用作保鲜剂，它利用了铁生锈的原理，所以又称“双吸剂”。这里的“双吸”是吸收空气中的         。有一袋铁粉使用了一段时间，表面已经生锈，经验证它还可以继续使用，其验证方法是加入过量的稀盐酸，写出有关反应的化学方程式       、        。

（18分）“从生活走进化学，从化学走向社会”。请你用化学知识回答以下生活中的问题：
（1）2011年3月15日央视曝光的“双汇瘦肉精”事件,是继“三鹿奶粉”事件后震惊国人又一大事件。瘦肉精的成分是盐酸克伦特罗，化学式为C₁₂H₁₉CI₃N₂O，瘦肉精是一种（填“有机”或“无机”）物，它含有种元素，它的一个分子中含有_________个原子；含氮元素的质量分数为 (结果保留到0.1%)。
（2）人被蚊虫叮咬后皮肤会红肿痛痒，这是由于蚊虫在被叮咬的皮肤内注入了少量的酸性物质所致。在被咬的皮肤上涂少许下列生活用品中的或 (填序号)，痛痒便会消失。

A．香油

B．肥皂水

C．纯碱水

D．糖水

（3）做馒头发酵面团时，会产生乳酸等有机酸，揉面团时需加入适量的纯碱或小苏打，让它们相互作用产生气体，使蒸出的馒头疏松多孔；若加入的纯碱或小苏打过多，可向面团或蒸锅中滴加少许酸性物质，如，否则蒸出的馒头会变涩，颜色发黄。
（4）工厂常用稀盐酸清洗铁制品表面的铁锈。该过程的化学方程式为。

维生素C（C₆H₈O₆）主要存在于蔬菜、水果中。近年来科学家发现，维生素C除具有人们所熟知的功效外，还具有防癌作用。但是蔬菜经过高温烹调，Vc将被破坏殆尽，所以一些绿色蔬菜经过油锅快炒即可。
⑴ 以上材料说明维生素C热稳定性       （填“好”或“差”）；
⑵ 维生素C常被添加入果汁饮料中作为营养增强剂，pH＜7时，维C比较稳定，所以在凉拌黄瓜时候可以加入      （从“食醋”和“面碱”中选择）作为调料能保持黄瓜营养；
⑶ 维生素C中碳、氧、氢三种元素的质量比是       。

Hi! My name is Hunt. Here is a picture of my class. Joan is short and is wearing a yellow dress. She is good at maths. David is tall and has black hair. He is good at playing basketball. He is on the school team. Mike is big. He has small eyes. He is funny. He can play football. Lily has long hair, she can speak Japanese.
Helen is a black girl. She has short hair. She likes swimming. She is on the swimming team. I like music. Can you find me? I'm the boy with glasses. Becky is new here. She comes from Hong Kong. She has black hair and black eyes. She speaks English well. And she is very good at computer.
(   )1.The colour of Joan's dress is ________.
A. blue               B. black            C. red               D. yellow
(   )2. ________ has long hair.
A. Joan               B. Lily             C. Helen            D. Becky
(   )3.Which is right?
A .David is short.                         B. Mike has long hair.
C. Helen is a white girl.                  D. Becky is good at computer.
(   )4.Hunt likes ________.
A. basketball        B .football        C .music            D. computer
(   )5.Helen is on the ________team
A. music            B. football        C. bashetball        D. swimming

One day, in an English class, the students are having their lessons. Their teacher, a young woman is very happy. She sings some nice songs with them and then she goes to the blackboard and writes “SMILES” on it. “This is the longest（最长）word in English,” she says to the class.
A girl stands up and says, “It has only six letters. How can it be the longest word in English?”
The teacher smiles and says, “Oh, look! There is a mile（英里）between the first letter and the last one.”
(     )6. One day, the students are having _________.
A. a good time   B. a big meal   C. a long meeting D. an English lesson
(     )7. The young woman sings some nice songs with __________.
A. her children   B. her students C. the teacher     D. a girl
(     )8. What does the teacher write on the blackboard?
A. A letter.      B. A word.      C. A song.       D. Her name.
(     )9. A girl _________ what the teacher says.
A. asks        B. believes(相信) C. doesn’t       D. doesn’t believe
(     )10. Is the word “SMILES” the longest in English?
A. Yes.         B. No.          C. Certainly.     D. Sure.

There is a new park near Andy’s home. It’s fine today. Andy and his family are in the park now. On their left, there is a café. On their right, there is a big lake. There are many flowers and trees around the lake. There’s a small hill behind the lake. Near the lake, there are two signs. One says, “Don’t swim in the lake!” The other says, “No fishing!” But you can go boating on the lake. There is a beautiful garden in the middle of the park. There are green grass and beautiful flowers in it. There are some small shops between the lake and the garden. The park is so nice. Andy and his family like it very much.
(   )11. The park near Andy’s home is ____________.      .
A. new and beautiful    B. old and beautiful   C. clean and new   D. old and clean
(   )12. Is there a café in the park? ---_____________.
A. Yes, there isn’t.      B. No, there isn’t.      C. Yes, there is.    D. No, there is.
(  )13. People can________ on the lake.
A. swim                 B. fish                C. boat              D. play
(   )14. The shops in the park are not _____________.      .
A. small                  B. big                 C. good            D. pretty
(   )15. Do Andy and his family like the park?  --__________.
A. Yes, they don’t.                      B. No, they do.
C. Yes, very much.                    D. No, they don’t.

A. 根据句意或中英文提示，写出单词的正确形式，每空一词。(8 分)
1. He is my ________ (双胞胎) sister, Kate.
2. Lucy is going to the ____________（博物馆）this winter holiday.
3. Kitty is small and she loves to ____________（跳舞）.
4.There are two ___________ (图书馆) in my school.
5. Tom is a ________ (有礼貌)boy. He always says "hello" to his teachers.
6.Would you like to be a m__________ of the Reading Club?—Of course..
7. He enjoys c_____ with his friends on the Internet .
8.Listen to me and a_____________ my questions.
B. 用所给词的适当形式填空。(7分)
9. Sunday is the ____________(one) day of a week.
10.. June 1^st is ____________ Day. (child)
11. Yao Ming is a very good basketball ____________. (play)
12. It’s time ____________(have) lunch.
13.Thank you for ____________(call) me.
14.May I ____________(borrow) your ruler?
15. I spend about an hour a day ____________(clean) the room.

完成句子。（共10个空格；每空1分，计15分）
1. “我爸每天下班后步行回家。
My father always _________   _________ after work every day.
2. 我表弟出生在英国。
My cousin Li Hai _________   _________ in England.
3. 请别在花园里爬树。
________   ________ the tree in the garden, please.
4..我们的足球队是世界上最好的队。
Our football team is ________ _______ in the world.
5.Deniel喜欢做飞机模型
Denniel likes _________   ___________ planes
6．汤姆喜欢玩电脑游戏，所以他戴眼镜。
Tom likes playing computer games, so he________ _______.    .
7．他不知道怎样娱乐。
He doesn’t know ______ _______ have __________.

	Name	Annie
	Age	13
	From	New York
	Love	Play computer games, singing, listening to music.
	Like	Wear beautiful clothes
	Dislike	exercise, Maths

__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Simon, Kitty says she a comic book in your home yesterday.

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