问题 解答题

如图是显微镜结构图,请根据图回答下列问题

(1)可以用来调节光线强弱的结构有[______]______和[______]______.

(2)[______]______转动时,可使镜筒作很小范围的升降.

(3)把玻片标本放在[______]______后,要用标本夹压住,标本要正对着______中央.

(4)用显微镜进行观察时,发现视野中有一污点,请分析:如果转动目镜和移动玻片标本,污点都没有随着移动,说明污点在[______]______上.

(5)实验室中的光线较弱,应选择______光圈和______镜.

答案

(1)显微镜视野亮度的调节方法为:小光圈通过的光线少,视野暗,平面镜只能反射光线不能改变光线强弱,因此用小光圈、平面镜调节会使视野变暗;大光圈通过的光线多,视野亮,凹面镜使光线汇聚,能提高视野的亮度,因此用大光圈、凹面镜调节,会使视野变亮.根据以上分析可知,在使用显微镜时,调节光线强弱的结构是遮光器上的光圈和反光镜.

(2)镜臂上有两种可转动的螺旋,一大一小,能使镜筒上下移动,调节焦距.大的叫粗准焦螺旋,位于镜臂的上方,可以转动,以使镜筒能上下移动,从而调节焦距,升降镜筒较快,用于低倍镜对焦;小的叫细准焦螺旋,位于镜臂的下方,它的移动范围较粗准焦螺旋小,升降镜筒较慢,较小幅度的升降镜筒外,还能调出更加清晰的物像.

(3)用显微镜观察时,把玻片标本放在载物台上后,用压片夹夹住,标本要正对通光孔的中央.

(4)转动目镜污点动就在目镜,不动就不在目镜;移动载玻片,污点移动就在装片,不动就不在装片;如果转动目镜和移动玻片标本,污点都没有随着移动,那就一定在物镜上.

(5)显微镜视野亮度的调节:光线强时,用小光圈、平面镜调节;光线弱时,用大光圈、凹面镜调节.如果在光线条件较差实验室里使用显微镜,应该使视野变亮,故用大光圈、凹面镜调节.

故答案为:8遮光器;9反光镜

(2)12细准焦螺旋

(3)7载物台;通光孔

(4)4物镜

(5)大光圈;凹面镜

阅读理解

阅读理解。

     Green-space facilities are contributing to an important extent to the quality of the urban environment.

Fortunately it is no longer necessary that every lecture or every book about this subject has to start with

the proof of this idea. At present it is generally accepted, although more as a self-evident statement than

on the base of a closely-reasoned scientific proof. The recognition of the importance of green-spaces in

the urban environment is a first step on the right way; this does not mean, however, that enough details

are known about the functions of green spaces in towns and about the way in which the inhabitants are

using these spaces.

     The theoretical separation of living, working, traffic and recreation which for many years has been

used in town-and-country planning, has in my opinion resulted in disproportionate (不成比例的)

attention for forms of recreation far from home, whereas there was relatively little attention for

improvement of recreative possibilities in the direct neighborhood of the home. We have come to the

conclusion that this is not right, because an important part of the time which we do not pass in sleeping

or working, is used for activities at and around home. So it is obvious that recreation in the open air has

to begin at the street door of the house. The urban environment has to offer as many recreation activities

as possible, and the design of these has to be such that more obligatory (强制性的) activities can also

have a recreative aspect.

     The very best standard of living is nothing if it is not possible to take a pleasant walk in the district, if

the children cannot be allowed to play in the streets, because the risks of traffic are too great, if during

shopping you can nowhere find a spot of enjoying for a moment the nice weather, in short, if you only feel yourself at home after the street door of your house is closed after you.

1. According to the author, the importance of green spaces in the urban environment _______.

A. is still unknown

B. is being closely studied

C. is usually neglected

D. has been fully recognized

2.The theoretical separation of living, working, traffic and recreation has led to _______.

A. the disproportion of recreation facilities in the neighborhood

B. all of the recreation facilities far from home

C. relatively little attention for recreative possibilities

D. the improvement of recreative possibilities in the neighborhood

3.The author suggests that the recreative possibilities of green spaces should be provided _______.

A. in special areas

B. in the suburbs

C. in the neighbourhood of the house

D. in gardens and parks

4. The author says "more obligatory activities can also have a recreative aspect" to _______.

A. suggest that obligatory activities don't need to serious

B. show that recreation activities are very important

C. show how recreation activities have spread wildly

D. suggest how to offer recreation activities around home

5. Why would someone only feel himself at home according to the last paragraph?

A. One lives the very best standard of living.

B. There are too many distractions outside his home.

C. There are few recreations around his house.

D. One needs the street door of his house to be opened always.

单项选择题