题目

Real policemen hardly recognize any resemblance between their lives and what they see on TV.The first difference is that a policeman’s real life revolved round criminal law. He has to know exactly what actions are crimes and what evidence can be used to prove them in court. He has to know nearly as much law as a professional lawyer, and what is more, he has to apply it on his feet, in the dark and rain, running down a street after someone he wants to talk to.Little of his time is spent in chatting. He will spend most of his working life typing millions of words on thousands of forms about hu探究“凸透镜成像特点”的实验时，请思考下列问题：（1）实验时，光屏上得到了一个清晰的像，但像的位置偏高如图所示（P点是2倍焦距处）。你解决的方法是 。（2）调整后，把蜡烛移到A点处，此时光屏上的像很模糊，为了得到清晰的像，应把光屏向 移动（选填“左”或“右”），这次成的倒立、 的实像；这一成像规律应用在 （选填“照相机”、“幻灯机”或“放大镜”）上。（3）再把蜡烛移到B点处，无论怎样调节光屏，光屏上始终接收不到像，是因为此时成的是正立、放大的像。要想看到这个像，应从图中的 点（选填“C”或“D”）箭头所示的方向去观察。