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问题 选择题

下面是一些光学知识的应用实例；其中应用光的直线传播的实例是（　　）

A．渔民用渔叉叉前方水中的鱼时，将渔叉对着稍低于所看到的鱼的位置叉去

B．在潜水艇中，用潜望镜观察水面上的景物

C．木工用一只眼睛沿一块木板楞的长度方向看过去，检查楞是否直

D．照相机的制作原理

答案

A、我们能看到水中的鱼，是由于鱼反射光线从水中射入到空气中的人眼里的缘故，故光线在水面处会发生折射，故渔民用渔叉叉前方水中的鱼时，将渔叉对着稍低于所看到的鱼的位置叉去，这是由于光的折射造成的，故该选项不符合题意；

B、由于潜望镜是利用平面镜成像的原理制成的，故在潜水艇中，用潜望镜观察水面上的景物的过程是利用光的反射原理，故该选项不符合题意；

C、木工用一只眼睛沿一块木板楞的长度方向看过去，检查楞是否直，这是利用光的直线传播的原理来工作的，故该选项正确；

D、照相机原理是利用凸透镜的成像规律制作而成的，故是利用光的折射的原理，故该选项不符合题意．

故选C．

单项选择题

Why is（）fun What delights may its practitioner expect as his reward First is the sheer joy of making things. As the child delights in his mud pie, so the adult enjoys building things, especially things of his own design. Second is the pleasure of making things that are useful to other people. Third is the fascination of fashioning complex puzzle-like objects of interlocking moving parts and watching them work in subtle cycles, playing out the consequences of principles built in from the beginning. Fourth is the joy of always learning, which springs from the（）nature of the task. In one way or another the problem is ever new, and its solver learns something: sometimes （）, sometimes theoretical, and sometimes both. Finally, there is the delight of working in such a tractable medium. The（）, like the poet, works only slightly removed from pure thought-stuff. Few media of creation are so flexible, so easy to polish and rework, so readily capable of realizing grand conceptual structures. Yet the program（）, unlike the poet’s words, is real in the sense that it moves and works, producing visible outputs separate from the construct itself. It prints results, draws pictures, produces sounds, moves arms. Programming then is fun because it gratifies creative longings built deep within us and delights sensibilities we have in common with all men.

The（）, like the poet, works only slightly removed from pure thought-stuff.

A．poet

B．architect

C．doctor

D．programmer
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单项选择题

水利工程质量由项目法人（建设单位）负（）责任。监理、施工、设计单位按照合同及有关规定对各自承担的工作负责。

A、直接

B、领导

C、部分

D、全面
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