大面积绿化有利于改善人类赖以生存的自然环境,这是因为绿色植物能( ) A.维持大

题型:选择题

问题:

大面积绿化有利于改善人类赖以生存的自然环境,这是因为绿色植物能(  )

A.维持大气中氧、二氧化碳相对平衡

B.使大气中氧含量保持不变

C.使大气中二氧化碳的含量保持不变

D.使大气中氧气和二氧化碳的含量不变

考点:绿色植物与生物圈中的碳—氧平衡
题型:选择题

质量相同的人造卫星,如果在不同轨道上绕地球做匀速圆周运动,那么下列判断中正确的是(  )

A.轨道半径大的卫星所受向心力大

B.轨道半径大的卫星所受向心力小

C.轨道半径大的卫星运行线速度大

D.轨道半径大的卫星运行线速度小

题型:选择题

When you think of the tremendous technological progress we have made, it’s amazing how little we have developed in other respects. We may speak scornfully of the poor old Romans because they enjoyed the seemingly excited killing that went on in their arenas(竞技场). We may despise them because they mistook these goings on for entertainment. We may forgive them because they lived 2000 years ago and obviously knew no better. But are our feelings of superiority(优越)really justified? Are we any less blood-thirsty? Why do boxing matches, for instance, attract such universal interest? Don’t the audience who attend them hope they will see some violence? Human beings remain as bloodthirsty as ever they were. The only difference between ourselves and the Romans is that while they were honest enough to admit that they enjoyed watching hungry lions tearing people apart and eating them alive, we find all sorts of arguments to defend sports which should have been banned long ago.

  It really is incredible that in this day and age we should still allow hunting or bull-fighting, that we should be prepared to sit back and watch two men punch each other in a boxing ring, that we should be relatively unmoved by the sight of one or a number of racing cars crashing and bursting into flames. Any talk of ‘the sporting spirit’ is merely hypocrisy(虚伪). People take part in violent sports because of the high rewards they bring. Audience are willing to pay vast sums of money to see violence. A world heavyweight championship match, for instance, is front page news. Millions of people are disappointed if a big fight is over in two rounds instead of fifteen. They feel disappointment because they haven’t experienced the exquisite pleasure of witnessing continuous violence.

  Why should we ban violent sports if people enjoy them so much? You may well ask. The answer is simple: they are uncivilized. For centuries man has been trying to improve himself spiritually and emotionally—though with little success. But at least we no longer tolerate the sight madmen imprisoned in cages, or public punishment of any of the countless other barbarous (野蛮的) practices which were common in the past. Prisons are no longer the harsh forbidding places they used to be. Social welfare systems are in operation in many parts of the world. Big efforts are being made to distribute wealth fairly. These changes have come about not because human beings have suddenly improved, but because positive steps were taken to change the law. The law is the biggest instrument of social change that we have and it may exert great civilizing influence. If we banned dangerous and violent sports, we would be moving one step further to improving mankind. We would recognize that violence is unworthy of human beings.

小题1:It can be inferred from the passage that the author’s opinion of nowadays’ human beings is ________________

A.not very high.

B.high.

C.scornful.

D.neutral小题2:Why does the author mention the old Romans in this article?

A.To reveal that the old Romans first started violent sports.

B.To prove that the old Romans were not civilized.

C.To show human beings in the past knew nothing better.

D.To indicate human beings today are as bloodthirsty as the old Romans.小题3:How many dangerous sports does the author mention in this passage?

A.Three.

B.Four.

C.Five.

D.Six.小题4:     What does the author want to illustrate in this article?

A. By banning the violent sports, we human beings can improve ourselves.

B. By banning the dangerous sports, we can improve the law.

C. We must take positive steps to improve social welfare system.

D. Law is the main instrument of social change.

题型:选择题

油机的基本结构主要由曲轴连杆机构、配气机构、供油系统、和冷却系统等部分组成。

题型:选择题

在管内加工螺纹使用()工具。

A.丝锥

B.板牙

C.螺母

D.螺帽

题型:选择题

伴随神九飞船安全返回的还有玉米、辣椒、茄子、番茄、刀豆等种子。航天育种,是指利用空间环境中宇宙辐射、微重力和弱地磁场等多种因素,诱使农业生物遗传变异,再通过严格的地面选育,获得优良农作物品种的过程。这从一个侧面表明()

①对真理的追求是永无止境的循环过程

②真理是理论与实践的具体的历史的统一

③客观事物的复杂性决定了认识的反复性

④认识只有不断超越历史条件才能成为真理

A.①②

B.①④

C.②③

D.③④

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