问题 问答题

如图所示,把凸透镜看作眼睛的晶状体,光屏看作视网膜.给凸透镜“戴上”近视眼镜,使烛焰在光屏上成清晰的像.“取下”近视眼镜,光屏上的像变模糊,沿靠近凸透镜方向移动光屏,光屏上能重新呈现清晰的像.实验结果表明:

(1)近视眼镜的作用是使像相对于晶状体向______(填“前”或“后”)移,从而能在视网膜上成清晰的像.

(2)矫正近视眼所配戴的镜片是______透镜.

(3)近视眼镜的作用是将光线______(填“会聚”或“发散”).

(4)请举出一项保护视力的具体做法:______.

答案

(1)近视镜片属于凹透镜,凹透镜对光线有发散作用,有近视镜片时,凸透镜所成的像会后移;

故答案为:后.

(2)近视眼是由于人眼的晶状体变凸,会聚能力增强,像呈在视网膜的前方,故应佩戴发散透镜,即凹透镜,使光线发散,.

故答案为:凹.

(3)近视眼是晶状体曲度变大,会聚能力增强,应佩戴发散透镜使光线推迟会聚,因凹透镜对光线有发散作用,所以近视眼应该配戴凹透镜才能看清远处的物体;

故答案为:发散.

(4)要保护视力,不要长时间上网看电视;不要躺在床上看书,不要再运动的车上看书等.

故答案为:不要躺在床上看书.

完形填空

In winter,when the sun hides behind the clouds,everyone feels a bit low. You may be tired and find you want to sleep all the time. What you may not know is:you are suffering from (患有) SAD(季节性抑郁症).

But don't worry—it's normal. Colder temperatures and fewer hours of daylight can steal your energy and put you in a bad mood.

Read on to find out what SAD is and what you can do to help yourself or those around you.

These days,Linda,a US teenager spends most of her holidays sleeping instead of doing sports outside. She has also had trouble concentrating(集中精力) on her homework. When her mother asks her what's wrong,Linda doesn't know what to tell her. Linda may not realize it yet,but she's suffering from SAD. It causes people to sleep,eat sweet food and get sad or angry for no reason.

About 15 percent of American people now suffer from SAD in winter according to the US Department of Health. The US government has taken measures to help people beat it. Local communities encourage people to take part in activities such as exercise,dance or art. And they advise people not to eat too much sweet food.

Like in the US,cold northern European countries such as Finland,Iceland and Russia see a large number of people suffer from SAD every year. So,the sunlamp is widely used in these countries. It's an electric lamp which is just like a “little sun” that gives off light to make people think the sun is shining and feel better.

小题1:Colder ________ and less ________ are the main causes of SAD.

小题2:Linda is feeling ________ and doesn't ________ doing sports because she's suffering from SAD.

小题3:      people suffer from SAD in        northern European countries.

小题4:In some northern European countries,the ________ is widely used to make people feel____ .

小题5:Taking an active part in ________ and eating ________ sweet food can help people beat SAD.

单项选择题