问题 填空题

常见的光学仪器在我们的生活、学习中应用广泛.照相时,被拍摄者应站在距镜头      处;投影仪能使投影片在屏幕上成倒立、    实像;借助放大镜看地图时,为使看到的像更大,应适当      放大镜与地图间的距离.

答案

2倍焦距以外(或大于2倍焦距);放大;增大

题目分析:(1)掌握凸透镜成像的三种情况和应用:

u>2f,成倒立、缩小的实像,物像的凸透镜的异侧,应用于照相机和摄像机.

2f>u>f,成倒立、放大的实像,物像的凸透镜的异侧,应用于幻灯机和投影仪.

u<f,成正立、放大的虚像,物像的凸透镜的同侧,应用于放大镜和老花镜.

(2)放大镜的成像特点:物距在一倍焦距内时,凸透镜成放大正立的像,且当物体离焦点近时,成的像较大.

根据凸透镜成像规律:物距大于二倍焦距成倒立、缩小实像,可知,照相时,被拍摄者应站在距镜头2倍焦距以外(或大于2倍焦距)处;

物距大于一倍焦距小于二倍焦距成倒立、放大实像,像距大于二倍焦距,应用是幻灯机、投影仪.

根据凸透镜的成像特点知,成正立放大的虚像时,离焦点越近时,像越大,为使看到的像更大,应适当增大放大镜与地图间的距离.

点评:此题考查了凸透镜的特点和成像原理及应用,要结合物理知识进行分析解答

完形填空
About a week ago, when I was playing basketball at our local park, I noticed a small group of boys picking on a smaller, skinnier boy. They were   31  him names and even pushed him to the ground and kicked dirt in his face.   32  I saw that, I walked over to the group.
I stepped   33  them and the smaller boy, and asked them politely what this boy had done worthy of   34  they were doing to him. One of the boys replied, “He’s weird.” At that, I asked one of the boys if he thought his friend was weird, and the   35  was “No.” So, I asked another boy what the word “weird”   36 , and he said, “Different.” That was my cue(暗示). I told them that everyone is   37 , and that they all looked just as different to the other boy as he did to them. They all stood   38  for a moment, and then the most amazing thing happened. One of the boys helped the small boy off the ground and then said sorry to him. He   39   to let him play with them.
I thanked the boy for being so   40 . As I looked around, I realized that there were dozens of other people at the park   41  no one else had stopped to help this boy. I felt happy that the boy was strong enough to stand up against his friends to   42  someone in need, but I felt sad that   43  else had even taken a second look.
I hope that my action helped them   44  that they could have made a difference with a little   45 , and maybe next time they will be the ones who choose to help.
小题1:
A.givingB.makingC.calling D.telling
小题2:
A.WhenB.Before C.IfD.Though
小题3:
A.againstB.betweenC.beside D.with
小题4:
A.howB.whyC.whomD.what
小题5:
A.guessB.signC.problemD.answer
小题6:
A.read B.provedC.meant D.wrote
小题7:
A.differentB.freeC.importantD.strong
小题8:
A.angrily B.silentlyC.carefullyD.happily
小题9:
A.refusedB.expectedC.offeredD.prepared
小题10:
A.proudB.cleverC.honestD.patient
小题11:
A.orB.soC.andD.but
小题12:
A.help B.stopC.loveD.remember
小题13:
A.someoneB.anyoneC.no oneD.everyone
小题14:
A.decideB.realizeC.suggestD.agree
小题15:
A.energyB.practiceC.knowledgeD.effort
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