下列烃中，苯环上的一氯代物的同分异构体数目最少的是（） A

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问题选择题

下列烃中，苯环上的一氯代物的同分异构体数目最少的是（）

A．邻二甲苯

B．间二甲苯

C．对二甲苯

D．乙苯

答案

答案：C

苯环上的一氯代物：邻二甲苯有2种；间二甲苯有3种；对二甲苯只有一种；乙苯则有3种。故而最少的为对二甲苯。

填空题

用所给词的适当形式填空.

1. Jim did___________ ( bad) of all the boys.

2. I was sorry __________ (hear) that he had a cold last week.

3. I hope you are in good___________ (health).

4. ___________(luck) , I passed the exam this time, and I was very happy.

5. To my _________(surprise), my mother took the train to my school yesterday.

6. lt was a __________ (disappoint) result, Lucy's friends were ___________ ( disappoint) to see it.

7. I didn't watch TV until I finish___________( do) my homework.

8. My Spanish teacher said my __________(listen) was good.

9. Mary said she was very ___________(luck) to get the prize.

10. He found science was__________( real) difficult.

填空题

凸轮机构按凸轮形状分主要有（）凸轮、（）凸轮和（）凸轮。