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问题 选择题

已知丙氨酸的结构简式为：，根据题意完成第23~26题：

23．丙氨酸中涉及到四种元素，它们的原子半径由小到大的顺序为           。

24．丙氨酸分子属于       （填“极性”或“非极性”）分子，一个丙氨酸分子中含有

     个非极性共价键。

25．丙氨酸分子中的氮原子核外有     个未成对电子，有     种不同能量的电子。

26．碳、氮、氧都可以形成氢化物，氧元素的氢化物除H2O外，还有H2O2，碳元素的氢化物除CH4外，还有C2H6等。与之相似的氮元素的氢化物的除NH3外，还有________，该氢化物与足量盐酸反应的化学方程式为______________________          。

答案

23．H＜O＜N＜C （1分）

24．极性；2。（2分）25．3；3。（2分）

26．N2H4；N2H4 + 2HCl → N2H6Cl2。（3分）

23．H原子半径最小，同周期从左到右减小O＜N＜C，答案：H＜O＜N＜C （1分）

24.丙氨酸分子不对称，是极性分子；分子中有2个C―C非极性共价键。（2分）

25．氮原子核外有3个未成对电子在2P轨道上；有3种不同能量的电子，在1S、2S、2P。三种轨道上（2分）

26．N2H4；与足量盐酸反应的化学方程式为N2H4 + 2HCl → N2H6Cl2。（3分）

单项选择题

( )是保险人签发保险单或承担保险义务，要求以投保人或被保险人必须履行某种义务为条件。其目的在于控制风险，确保保险标的及其周围环境处于良好的状态中。

A．保证
B．告知
C．承诺
D．确认
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完形填空

    Of all the men who ever liked fresh air, no one liked it more than James Wilson did. He _1__ slept with his window open even when snow was falling outside.

One winter, he went to Finland on business. When he _2__ his room in the hotel, he found that the windows were closed to __3__ the icy air out. He did his best to open one but failed. The bed was really __4___, but Wilson couldn’t sleep. He __5__ forget the closed windows. No fresh air! It was __6___ to think of.

At about one o’clock in the morning, he was __7__ awake. Worrying about the air in the room. He became very angry. Where was the __8__ ? He could see something that looked like __9___ over there. He threw a shoe at it through the darkness with all the force of his strong right arm. A terrible sound of breaking glass _10__ the room, but to Wilson’s sad heart, it seemed like the sound of __11___ music.

When daylight came through the window, he __12___ and lay with his eyes close. There was __13__ to worry about. __14___ was it ? Oh, the broken window! Yes, indeed. He would have to pay __15__ that. He opened his eyes to look.

Suddenly he sat up in __16__. The window was not broken at all. The __17__ was all in one piece, just as good as it had been the night before. __18__ fresh air was entering the room through the window!

He then turned his eyes to the __19__ and saw a broken picture __20__ on the wall. There was a shoe on the floor below it, and a lot of broken glasses around the shoe.

1. A. seldom           B. often                 C. sometimes          D. always

2. A. left             B. cleaned               C. entered            D. examined

3. A. prevent          B. keep                  C. stop               D. send

4. A. cold             B. comfortable           C. bad                D. terrible

5. A. shouldn’t       B. wasn’t able to       C. couldn’t          D. wouldn’t

6. A. unlucky          B. anxious               C. difficult          D. terrible

7. A. already          B. nearly                C. hardly             D. still

8. A. waiter           B. manager               C. window             D. light

9. A. paper            B. glass                 C. a picture          D. a man

10. A. destroyed       B. covered               C. filled             D. entered

11. A. funny           B. strange               C. beautiful          D. famous

12. A. got up          B. woke up               C. went in            D. came down

13. A. a lot           B. little                C. something          D. someone

14. A. What            B. How                   C. Where              D. Who

15. A. to              B. with                  C. from               D. for

16. A. silence         B. surprise              C. trouble            D. pain

17. A. window          B. picture               C. glass              D. shoe

18. A. Much            B. No                    C. Still              D. Yet

19. A. outside         B. top                   C. side               D. bottom

20. A. lying           B. hanging               C. falling            D. put    
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