问题 选择题
如图所示为一磁流体发电机示意图,A、B是平行正对的金属板,等离子体(电离的气体,由自由电子和阳离子构成,整体呈电中性)从左侧进入,在t时间内有n个自由电子落在B板上,则关于R中的电流大小及方向判断正确的是(  )

A.I= ,从上向下

B.I= ,从上向下

C.I= ,从下向上

D.I= ,从下向上

答案

答案:A

阅读理解与欣赏

飞沙滩观夜潮

  ①到过许多的海,东海、南海、渤海……甚至看过太平洋、大西洋,也看过许多写海的诗文。东海观红日,南海赏银月,渤海戏碧浪。海像一面多棱镜,永远闪着云谲波诡的光。海浪、沙滩、日光、月辉、贝壳,是咏海的诗文中最基本的元素。海,常给人以壮阔、浩淼、雄浑博大之印象,吐纳百川,荡涤污秽。

  ②惟独,没有领略过被无月的夜幕笼罩下的大海的姿容。

  ③想像着,那一定很乏味。无月无星的夜晚,天空似一幅硕大无比泼了墨的画布,几乎连云彩的轮廓也辨不清,只依稀瞧见洇洇湿湿的墨迹。

  ④这是一个名气尚不太响的海滩飞沙滩,中国第一侨乡台山市南部上川岛东部的一个海滨浴场,却拥有一流海滨浴场所必备的一切基本条件。

  ⑤赤脚站在飞沙滩那平坦、细腻却又硬实的沙地上,远远地看着海浪汇聚成一牙一牙的银色花边,镶嵌在奔涌的黛色海潮周围,似一幅翻卷、飘舞的裙裾。只是,望穿双眼也看不到舞者芳容,黛色遮掩了一切。

  ⑥听不见壮阔的轰鸣,看不见惊涛拍岸的飞浪。大海怎会如此乖巧?夜潮怎会如此温柔?

  ⑦顺着退潮后裸露出来的大片平坦而细腻的沙滩向海里走,想用双脚和身体去触摸看起来温柔有加的夜潮。

  ⑧别看海潮时常用咆哮、怒吼的面孔来显示它的威严、雄壮、凛然不可侵犯的模样,飞沙滩只是张开五千米特别平滑柔顺的臂弯拥抱了它一下,就把它从大海深处聚集的力量缓缓地释放掉,令其呈现一派轻吟低唱的姿容。飞沙滩以其柔克海之刚烈,让人们领略到大自然刚柔相济之美。

  ⑨优哉游哉地趟着扑到沙滩上的海浪,走到海水触膝的位置,静静地望着泛起白沫的海潮,想再体验一下海的温柔。不料想,只定定地盯着海面看了一分钟,温柔的海潮霎时换了面孔,忽然变得深不可测,一种森然的感觉顷刻袭上心头,并迅速灌注了全身。

  ⑩瞧!远望的海潮似镶嵌着银色花边舞动着的裙裾,近观的海潮却演变成千万条银蛇,黛色的大海似乎是一个深不见底黑洞洞的蛇窝,无休止地撒出一条条银蛇,贴着地皮朝着沙滩迅疾游来。

  莫非,大海在雄浑壮阔的常态之外,既有温柔婉约的情愫,也有阴森可怖的梦魇?

  我踉跄地后退了几步,惊诧于海的倏忽幻异,感叹大海对不同距离的观察者展示的不同特质。

  忽然顿悟,大海之所以世世代代被人们咏叹,激人们抒情壮怀,永不厌倦,永不乏味,实在是因为它太博大、太变幻莫测。大海实在是过于博大深奥了。人类在大海面前永远如学步的儿童,睁着好奇的双眼,费尽气力探索着这个蓝色的万花筒,刚刚看清了里面的一个几何图形的碎片,却见她波光一闪,一个新的图案又如一道难题呈现在眼前,人类世世代代会有许多精英为破译海的神秘耗尽毕生的心血和才华。

  飞沙滩,下一次再见面的时候,你会给我一个怎样的新感觉呢?

1、从文中找出三个以上的成语。

 _________________________________________________

2、文章的第①段概括地描述了各地的海景,这与下文写飞沙滩夜潮有什么关系?

 _________________________________________________

3、第③段所写的是作者的想像,其想像的景象与下文的无月夜潮形成怎样的关系?说一说这样写的好处。

 _________________________________________________

4、作者从两个角度来写飞沙滩的夜潮,一个是远望,一个是近观。仔细阅读文章的第④~⑩段,回答下列问题。

(1)远望大海,大海所呈现的最显著的特点是_______,而夜潮则显得_______。飞沙滩用它宽广的胸膛和柔顺的臂弯,使大海呈现出了轻吟低唱的姿容。

(2)解释“黛”字的含义,大海为什么呈现出“黛色”?

 _________________________________________________

(3)作者近观海潮,海又呈现出怎样的特点?

 _________________________________________________

5、作者在观潮后,对海的特点有了更新的认识,请你总结一下海有哪些特点?

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阅读理解
阅读下列短文,从每小题所给的四个选项(A. B. C和D) 中,选出最佳选项。
Is veg food healthier than non-veg food? I feel this is a very common topic that people speak on.Please give me your opinions on this topic.
Rao
12-18-08
So far as veg food is concerned, it is also proved to be a healthy and nutritious diet, but has very few items which can provide us with proteins, but if you see non-veg food like eggs, chicken, and many more, such foods have a large content of proteins in them.
Sai
12-19-08
Man basically is herbivorous(食草的). If we look at the animal kingdom
We can see that all the herbivorous animals have the similar dental(牙齿的)
structure, which clearly shows that the human being also ought to be vegetarian
by birth. It is only the living conditions that make man carnivorous(食肉的).
The vegetarian foods are easily digestible.
Santos
12-20-08
Non-veg food items are better than veg items. A healthy person requires complete diet and veg+ meat makes the diet complete. The only caution that needs to be taken is not to have non-veg items on a daily basis. Once in a week or couple of weeks will be best.
Krishna
01-03-09
When we eat non-veg, we are all veg by nature. The chicken that we eat feeds on grains, the mutton that we eat feeds on grass, and the fish that we eat feeds on simple plants. So non-veg food by logic(逻辑)is better and suited for hauman beings.
Khan
01-05-09
Non-veg food is equally important in our diet as it helps in many ways, especially fish and other seafood as fish contains omega 3 which makes our immune system(免疫系统)stronger. Do you know that most of the veg food put together does not contain as much omega 3 as fish alone contains!
Khan
01-05-09
Non-veg food is equally important in our diet as it helps in many ways, especially fish and other seafood as fish contains omega 3 which makes our immune system(免疫系统)stronger. Do you know that most of the veg food put together does not contain as much omega 3 as fish alone contains!
小题1:According to Rao, what is the problem with veg food?
A.It damages our immune system.B.It has few nutrients.
C.It contains too much omegaD.It is lacking in protein.
小题2:In the opinion of Sai, humans are born vegetarian because humans______.
A.have the same teeth structure as plant-eating animals
B.believe that veg foods are good for their teeth
C.belong to the plant-eating animal family
D.can adapt to the living conditions like plant-eating animals
小题3:What advice is given by Santos?
A.To have a saily veg+ meat diet.
B. Not to eat non-veg food every day.
C.To eat digestible food every day.
D.Not to eat food without protein.