问题 实验题

下图是显微镜的结构图,请据图回答下列问题(短线上填有关文字,[ ]内填图中字母)。

(1)对物像有放大作用是的[A]       和[D]       。如果一台显微镜,[A]的放大倍数为10×、[D]的放大倍数为40×,则物像的放大倍数为       倍。

(2)能反射光线的是[       ]反光镜。

(3)在显微镜视野中看到的物像是“b”,则载玻片上的字母是“       ”。

(4)为了使显微镜视野中的物像更加清晰,可以调节[K]       

答案

(1)目镜   物镜   400  (2)H  (3)q   (4)细准焦螺旋

题目分析:(1)目镜是用眼观察的镜头,物镜是接近物体的镜头,显微镜中起放大作用的结构是物镜和目镜,物像的放大倍数是目镜的放大倍数乘以物镜的放大倍数,所以该显微镜的放大倍数是400倍;

(2)反光镜的作用是反射光线,有平面镜和凹面镜两个面,当外界光线较强时用平面镜,当外界光线较弱时用凹面镜;

(3)显微镜看到的物像不但上下颠倒,左右也颠倒,做此类题有个小诀窍,就是把这个字母写到一张小纸上,然后把这张纸旋转180度再看就是左右上下颠倒的图象了,玻片标本上的是“b”,那么显微镜下看到的是“q”字;

(4)细准焦螺旋的作用是较小幅度的升降镜筒,更重要的作用是能使焦距更准确,调出更加清晰的物像,因此在观察的过程中物像不够清晰,应该通过调节细准焦螺旋使物像清晰。

阅读理解

Homework should be done as soon as you get home from school. If you have after-school activities, the homework should be done first. At the same time, it is fine to allow(允许)for a snack break and also to allow for stretching(拉伸的)breaks.

Also, you should remember that it is your duty to do your homework. Next time, when you want to depend on(依靠) Mom and Dad for help, please try to find the answer yourself, because you will learn much, much more that way.

When you have a question, especially something about a science or math, don’t always turn to your teacher! It is a good idea to try to find the answer yourself. If this doesn’t work, you can also look at the materials in the back of the book. They may guide you to the pages you should look at to help you understand the problem.

Finally, while doing homework, don’t think about or do other things. Keep working. Setting a time limit(限制) often helps with this. Different ages decide different amounts of time. 10-15 minutes is good for a child that’s aged 6-8. A time of 20-30 minutes is about right for a child aged 9-12. Kids can keep studying for 30-45 minutes from the ages of 13 to 15. This, of course, depends on your abilities to pay attention and stay on tasks.

小题1:In the first paragraph, the writer mainly tells us that ______.

A.doing homework is the first thing you should do at home

B.after-school activities can’t affect doing homework

C.parents can help kids with their homework at night

D.kids need a good rest after school小题2:In the third paragraph,   the writer wants to tell us that ______.

A.students should ask the teacher more questions

B.thinking over the questions before asking others is important

C.problems can’t be solved without a teacher’s help

D.students shouldn’t always look at the materials in the back of the book小题3:The passage mainly tells children ______.

A.not to look away while doing homework

B.to do homework by themselves

C.not to turn to teachers when doing homework

D.to do their homework quickly and in the right way’

填空题