题干

小明做“研究近视眼的矫正”实验中,他把凸透镜看作眼睛的晶状体,光屏看做眼睛的视网膜,烛焰看作是眼睛观察的物体。小明拿一个近视眼镜放在凸透镜前,光屏上出现烛焰清晰的像,如图所示。而拿走近视眼镜则烛焰的像变得模糊,下列操作能使光屏上重新得到清晰像的是(    )

A:将光屏适当远离凸透镜

B:将蜡烛适当远离凸透镜

C:将光屏适当靠近凸透镜或将蜡烛适当靠近凸透镜

D:将光屏适当远离凸透镜或将蜡烛适当远离凸透镜

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答案(点此获取答案解析)

C

同类题4

阅读理解

B

    In choosing a friend, one should be very careful. A good friend can help you study. You can have fun together and make each other happy. Sometimes you will meet fair-weather friends. They will be with you only if you have money or luck, but when you are down, they will run away. How do I know when I have found a good friend? I look for certain qualities of characteristic, especially understanding, honesty and reliability (可靠).

    Above all else, I look for understanding in a friend. A good friend tries to understand how another person is feeling. He is not quick to give his opinion. Instead, he tries to learn from others. He puts himself in the other person's place, and he tries to think of ways to be helpful. He is also a good listener.

    At the same time, however, a good friend is honest. He does not look for faults (过错) in others. He notices their good points. In short, a friend will try to understand me and accept me.

    Another quality of a friend is reliability. I can always depend on (信赖) a good friend. If he tells me he will meet me somewhere at a certain time, I can be sure that he will be there. If I need help, he will do his best to help me. If I am in trouble, he will not run away from me.

    There is a fourth quality that makes a friend special. A special friend is someone with whom we can have fun. We should enjoy our lives, and we would enjoy our friendship. That is why I especially like friends who are fun to be with. A good friend likes the same things I like. We share experience (经验) and learn from each other. A good friend has a good sense of humour, too. He likes to laugh with me. That is how we share in the joy of being friends. And I know that he is looking for the same quality in me.

    When I meet someone who is reliable, honest, and understanding, I know I've found a friend!

同类题5

发展中国特色社会主义是历史的必然选择。阅读下列材料,回答问题。
【发人深省的往事】   1958年几千万人开始大炼钢铁,不仅钢铁厂开足马力,土高炉也遍地开花,到了10月底就达到了几百万座。……1958年夏秋之际,各地纷纷成立人民公社。公社的一切财产统一核算,统一分配;公社还大办公共食堂,实行吃饭不要钱,“鼓足干劲生产,放开肚皮吃饭”是当时流行的口号。
(1)上述材料反映出我党在探索社会主义建设道路过程中的严重失误是什么?
【回味无穷的话语】 “革命是解放生产力,改革也是解放生产力,中国农村改革的发明权属于农民。”“在你们广东划出一块地方来,也搞一个特区……过去陕甘宁边区是特区。中央没有钱,你们自己搞,要杀出一条血路来。”                 ——《邓小平文选》
(2)改革开放的伟大决策是在党的哪次会议上做出的?此次会议的指导思想是什么?
(3)在农村改革中,采取的具体措施是什么?此措施起到了怎样的作用?
(4)请列举1980年建立的经济特区,并说说经济特区在社会主义现代化建设中发挥了怎样的作用?
【鼓舞人心的数据】

时间国内生产总值工业增加值粮食产量城镇居民人均可支配收入
1978年3642亿元1607亿元30477万吨343元
2007年246619亿元107367亿元50150万吨13786元

(5)以上数据的变化说明了什么?从这一变化中,我们可以得到什么启示?