- 光的折射
- 共2353题
人们对光的认识经历了一个漫长的过程,下列有关对光的阐述中正确的是
[ ]
正确答案
在没有月光的夜间,一个池面较大的水池底部中央有一盏灯(可看做点光源),小鱼在水中游动,小鸟在水面上方飞翔,设水中无杂质且水面平静,下列说法正确的是( )
正确答案
下列说法正确的是( )
正确答案
在两种介质的界面处发生全反射,由此可判定:( )
①光由光密介质射向光疏介质②光由光疏介质射向光密介质
③入射角等于或大于临界角④入射角小于临界角.
正确答案
关于从空气射入玻璃中的一束单色光,下列说法正确的是( )
正确答案
光线在玻璃和空气的分界面上发生全反射的条件是( )
正确答案
关于光的现象,下列说法正确的是( )
正确答案
已知某玻璃对蓝光的折射率比对红光的折射率大,则两种光
[ ]
正确答案
红、黄、蓝三束单色光,在某介质内以相同的入射角射入真空中,下列说法中正确的是
[ ]
正确答案
下列情况中,包含全反射情况的是
[ ]
正确答案
下列有关光现象的说法正确的是
[ ]
正确答案
Asia’s real boat-rocker is a growing China, not Japan, a senior American economist observed.
There is so much noise surrounding and emanating from the world’s miracle economy that it is becoming cacophonous. In Washington, D. C., the latest idea is that China is becoming too successful, perhaps even dangerously so: while Capitol Hill resounds with complaints of trade surpluses and currency manipulation, the Pentagon and sundry think-tanks echo to a new drumbeat of analysts worrying about China’s 12.6% annual rise in military spending and about whether it might soon have the ability to take preemptive military action to force Taiwan to rejoin it. So it may be no coincidence that for
three consecutive weekends the streets of big Chinese cities have been filled with the sounds of demonstrators marching and rocks being thrown, all seeking to send a different message: that Japan is the problem in Asia, not China, because of its wanton failure to face up to its history; and that by cosying up to Japan in security matters, America is allying with Asia’s pariah.
Deafness is not the only risk from all this noise. The pressure towards protectionism in Washington is strong, and could put in further danger not only trade with China but also the wider climate for trade liberalisation in the Doha round of the World Trade Organisation (WTO). So far words have been the main weapons used between China and Japan, but there is a chance that nationalism in either or both countries could lead the governments to strike confrontational poses over their territorial disputes in the seas that divide them, even involving their navies. And the more that nationalist positions become entrenched in both countries but especially China, the more that street protests could become stirred up, perhaps towards more violence.
All these issues are complex ones and, as is often the case in trade and in historical disputes, finding solutions is likely to be far from simple. A revaluation of the yuan, as demanded in Congress, would not rebalance trade between America and China, though it might help a little, in due course. A "sincere" apology by Japan for its wartime atrocities might also help a little, but it would not suddenly turn Asia’s natural great-power rivals into bosom buddies. For behind all the noise lies one big fact: that it is the rise of China, not the status or conduct of Japan, that poses Asia’s thorniest questions.What is the main cause of the issues in Asia according to the author()
A.Trade and historical disputes.
B.The appreciation of the yuan.
C.Japan's refusal of apology for its wartime atrocities.
D.The rise of China.
正确答案
D
解析
推理题。文章最后一句提到“因为在所有这些嘈杂之后存在着一个巨大的事实:是中国的崛起而不是日本的地位和行为造成了亚洲棘手的问题”,由此可推知作者认为[D]“中国的崛起”是亚洲问题的主要原因。[A]“贸易和历史争端”,[D]“人民币的升值”和[C]“日本拒绝为其战时暴行道歉”都不是文中提及的主要原因。
下述不符合血细胞发育过程中形态演变规律的是
A.胞体由大至小
B.胞浆量由多至少
C.颗粒从无至有
D.核仁从有至无
E.核染色质由细致至粗糙
正确答案
B
解析
暂无解析
下列有关我国古代四大发明的表述,正确的是______
A.西汉时期蔡伦改进了造纸术
B.隋唐时期已经有了活字印刷的书籍
C.唐朝时发明了管形火器“突火枪”
D.宋代在航海交通上已普遍使用指南针
正确答案
D
解析
[解析] 本题中改进造纸术的是东汉蔡伦,隋唐时的印刷技术属于雕版印刷,管形火器“突火枪”是在南宋发明的,A、B、C三项都不正确,故正确答案为D。
上消化道出血的范围是
A.幽门以上出血
B.贲门以上出血
C.Treitz韧带以上出血
D.空回肠交界处以上出血
E.回盲部以上出血
正确答案
C
解析
[解题思路] 上消化道出血是指Treitz韧带以上的出血。[命题规律] 考察“上消化道出血的概念”。重点掌握。
扫码查看完整答案与解析