问题 选择题

用目镜为5×,物镜为10×观察叶片的横切面,可以看到排成一排的表皮细胞中的10个.若物镜不变,目镜换成10×时,则在视野中可看到这排细胞中的(  )

A.5个

B.15个

C.20个

D.30个

答案

通过分析题目中第一次观察是放大倍数是5×10,是50倍,可以看到排成一排的表皮细胞中的10个;第二次观察是放大倍数是10×10,是100倍,是第一次的二倍,又因为显微镜的放大倍数与视野中可看到细胞的数目成反比例关系,所以应是第一次的二分之一,5个.

故选:A.

改错题
短文改错。
     此题要求改正所有短文中的错误。对标有题号的每一行做出判断:
如有错误(每行只有一个错误),则按下列情况改正:
此行多一个词:把多余的词用斜线(\)划掉,在该行右边横线上写出该词,并也用斜线划掉。
此行缺一个词:在缺词处加一个漏字符号(),在该行右边横线上写出该加的词。
此行错一个词:在错德词下划一横线,在该行右边横线上写出改正后的词。
注意:原行没有错的不要改。
After five years away in my hometown, I find that                
the neighborhood which I used to living in has changed           
A lot. The Sichuan Restaurant and the older fish shop            
across the street from our middle school were gone.               
There exist now a park that has a small river running            
through. The factory at the corner of Friendship Street or      
Zhongshan Road has been moved out of the city, and sports        
center has been built in their place. The market at the corner of
friendship Street and Xinhua Road has been given way to         
a supermarket. Besides the bookstore next to our middle          
school is still there.                                           

1______
2______
3______
4______
5______                  
6______
7______
8______
9______
10______

问答题 简答题