完形填空

    The world has many beautiful 1. We can hear the songs of birds and the laugh of people. We can listen to cool music and news reports. And it is all because of our ears! They 2 us a world of sounds.

    But some people can't hear any sound at all. Some are born deaf. 3can hear well in their childhood, but too many loud sounds hurt their ears later on.

 Many people in China can't hear ordinary sounds clearly. A large number of them are children. Most of them are born 4 good hearing. But six children out of every 1,000 have hearing problems when they are born.

    A lot of things can5 hearing problems. And noise louder than 85 decibels(分贝) can hurt our ears and make us lose our hearing for a short time or even forever.

Hearing is important. So we should do our best to give our ears special care. Don't forget to do the following:

    Try to 6 places with too much noise. When 7, remember to put earplugs into your ears to stop water from getting in.

     Never put 8 sharp (尖锐的) into your ears. Keep these things in 9! Then you won't 10“What? What?” when you are older.

现代质谱仪可用来分析比质子重很多的离子，其示意图如图所示，其中加速电压恒定．质子在入口处从静止开始被加速电场加速，经匀强磁场偏转后从出口离开磁场．若某种一价正离子在入口处从静止开始被同一加速电场加速，为使它经匀强磁场偏转后仍从同一出口离开磁场，需将磁感应强度增加到原来的12倍．此离子和质子的质量比约为（   ）

科学研究证明，烟草燃烧时，烟雾中含有多种对人体有害的物质，如____、____等。这些物质进入人体，不仅能诱发多种____疾病，还有诱发____。