题干

楼道里,夜间只是偶尔有人经过,电灯总是亮着会浪费电能.科研人员利用光敏材料制成“光控开关”,天黑时自动闭合,天亮时自动断开.利用声敏材料制成“声控开关”,当有人走动发出声音时,自动闭合;无人走动时,自动断开.若将这两种开关配合使用(如图),就可以使楼道灯变得“智能化”,这种“智能”电路正确的是(   )

A:

B:

C:

D:

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A

同类题2

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    There were three big fish in the lake. One of them, Demo, was wise; another one, Jimmy, was half-wise; Martin, the third one, was stupid.

    Some fishermen came to the bank of the lake with their nets. The three fiss saw them.

    Demo decided at once to leave, to make the long and difficult trip to the ocean. He thought, "I won't discuss with these two about this. They love this place so much that they call it home and will stay on. How silly they are! They still haven't realized we are in great danger now. Their ignorance will cost them their lives."

    Seeing the wise fish had left, Jimmy thought, "My guide has gone and now I've lost my chance to escape." He felt sorry for it and then thought, "What can I do to save myself from these men and their nets? Perhaps I should pretend(假装)to be already dead, giving myself totally to the water."  So he did that. He went up and down with the water, helpless, within arm's reach of the fishermen.

    "Look at this! The best and biggest fish is dead." One of the men lifted him by the tail, and threw him up on the ground. He rolled(滚动)over and over and moved secretly toward the water, and then, back in.

    The third fish was aimlessly jumping about, trying to escape with his speed and cleverness. The net, of course, finally closed around him, and as he lay in the hot frying-pan bed, he thought, "If I get out of this, I'll never live again in the limits of the lake. Next time, the ocean! I'll make it my home."