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【单选题】
'Water, which is essential for life, costs nothing. On the other hand, diamonds, which are essential for nothing, cost a lot.' Unfortunately, the world has changed considerably since an 18th century economist made this remark. What was true over 200 years ago is certainly no longer true now. In a number of countries people pay as much for water in their homes as they do for electricity. Like health, we ignore water when we have it--unless there are floods, of course. Once there is a threat to our water supply, however, water can quickly become the only thing that matters. We know only too well that, without water, there can be no life. The situation is now becoming so bad that environmentalists feel it may be necessary to shock the world into saving water in a similar way to the shock caused by the oil crises in the 1970's. At that time, the oil crisis became such a serious threat to the lives of everyone in the developed countries that it made people conscious of the importance of saving oil and provided powerful encouragement for governments to look for other forms of energy. The result undoubtedly was of major benefit to energy conservation. There is now no longer an unlimited supply of fresh water. About 97 percent of the planet's water is seawater. Another 2 percent is locked in icecaps and glaciers. There are also reserves of fresh water under the earth's surface but these are too deep for us to use economically. Unfortunately, competition is growing fiercely for what little water is available. It may be a matter of time before that competition becomes a conflict. To make matters worse, the world's population is increasing so rapidly that it is expected to grow to about 8 billion in 15 years. Moreover, in many developed countries throughout the world, flush lavatories and washing machines mean the average person now uses 300 litres of water a day compared with 50 at the beginning of last century. At the other extreme, according to the World Health Organization, one quarter of the world's present population still lacks safe drinking water and proper sanitation. Most live in the southern hemisphere, where supplies of fresh water are put in jeopardy through dirty industrial practices, poor irrigation and erosion. The social stability of the world is no longer threatened by global wars, the Cold War. However, the supply of water could soon become the chief threat to such stability. There is already evidence of this happening, especially in Africa. Recently the Egyptian Government threatened to destroy any dams built on the Nile if they considered the dams would affect their supply of fresh water. What is required immediately is an awareness of the true value of water and the formation of sensible water conservation strategies. It is also of vital importance to have a consensus on how best to use shared water resources for the benefit of all the countries in the world as well as an examination of the best methods for the distribution of the world's water. According to the passage, which of the following statements is true?
A.
People now pay as much for water as they did 200 years ago.
B.
People now pay as little for water as they did 200 years ago.
C.
Water now costs as much as it used to.
D.
Water now has become more expensive than it was.
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【简答题】琪琪和表姐小薇差半岁,同时上了幼儿园小班。由于小薇爸爸妈妈工作忙,不久她被送到了小镇上奶奶家。小镇幼儿园的老师非常强调知识学习,一年后,小薇已经能认许多字了,而琪琪却整天沉浸在游戏中,几乎不用学习,一个字也不认得。爸爸妈妈开始为此担心,怕幼儿园这样的教学会影响琪琪今后的学习。你觉得琪琪父母的担心有必要吗?为什么?
【简答题】琪琪和表姐小薇差半岁,同时上了幼儿园小班。由于小薇爸爸妈妈工作忙,不久她被送到了小镇上奶奶家。小镇幼儿园的老师非常强调知识学习,一年后,小薇已经能认许多字了,而琪琪却整天沉浸在游戏中,几乎不用学习,一个字也不认得。爸爸妈妈开始为此担心,怕幼儿园这样的教学会影响琪琪今后的学习。 你觉得琪琪父母的担心有必要吗?为什么?
【单选题】下列有关神经兴奋的叙述,正确的是()
A.
静息状态时神经元的细胞膜内外几乎没有离子进出
B.
突触间隙中的神经递质经主动运输穿过突触后膜而传递兴奋
C.
神经细胞兴奋时细胞膜对Na+通透性减小
D.
兴奋在反射弧中以神经冲动的方式单向传递
【单选题】1 17 5 . 设地面A、B两点相距80m,水准仪安置在中点C,用两次仪器高法测得hAB=-0.347m,仪器搬至A点附近3米处,测得A点水准尺读数a2=1.456m,B点水准尺读数b2=1.752m,则仪器的视线( )
A.
向上倾斜
B.
向下倾斜
C.
水平
D.
可能向上倾斜也可能向下倾斜
【简答题】阅读下列材料,回答问题。 琪琪和表姐小薇差半岁,同时上了幼儿园小班。由于小薇爸爸妈妈工作忙,不久她被送到了小镇上的奶奶家。小镇幼儿园的老师非常强调知识学习,一年后,小薇已经能认许多字,而琪琪却整天沉浸在游戏中,几乎不用学习,一个字也不认得。爸爸妈妈开始为此担心,怕幼儿园这样的教学会影响琪琪今后的学习。 问题:你觉得琪琪父母的担心有必要吗?为什么?
【单选题】下列有关神经兴奋的叙述,正确的是
A.
静息状态时神经元的细胞膜内外没有离子进出
B.
组织液中Na+浓度增大,则神经元的静息电位减小
C.
.突触间隙中的神经递质经主动运输穿过突触后膜而传递兴奋
D.
神经纤维接受刺激产生的兴奋以电信号的形式传导
【单选题】下列有关神经兴奋的叙述,正确的是()
A.
静息状态时神经元的细胞膜内外没有离子进出
B.
神经元的静息电位就是膜电位为零
C.
突触间隙中的神经递质经主动运输穿过突触后膜而传递兴奋
D.
神经纤维接受刺激产生的兴奋以电信号的形式传导
【单选题】下列有关神经兴奋的叙述,正确的是______
A.
静息状态时神经元的细胞膜内外没有离子进出
B.
组织液中Na + 浓度增大,则神经元的静息电位减少
C.
突触间隙中的神经递质经主动运输穿过突触后膜而传递兴奋
D.
神经纤维接受刺激产生的兴奋以电信号的形式传导
【判断题】在某测站上测得A、B点上两水准尺黑面高差为+0 .833m,红面读数分别为a=6 071mm,b=5 139mm,则A、B点的高差中数hAB=0. 882m。
A.
正确
B.
错误
【单选题】设地面上有A、B两点,两点的高程分别为HA=19.186m,HB=24.754m,则A、B两点的高差hAB=
A.
5.672m
B.
-5.568
C.
5.568m
D.
-5,672
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