题干

两个完全相同的容器分别盛有质量相等的水,将木块A和金属块B按不同的方式放入水中.A、B静止时的情况如图所示,(设细绳的重量和体积不计)则下列判断正确的是(   )

A:甲图容器底部受到水的压强较大

B:甲图木块下表面受到水的压强较小

C:甲、乙图容器底部受到水的压强大小相等

D:甲图木块受到的重力大于乙图木块受到的重力

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C

同类题4

阅读下列材料,回答问题:
材料一:拜占廷的作用是绝对保守的。命运注定它只是保存,而不是创新。它诞生在一个古老的国度,生活在过去的努力和荣誉的阴影之中,这种势力和荣誉正是它所试图维持和恢复的。他们很少有人具有创造力。
材料二:落后、保守的查士丁尼(527-565年)一心想将恢复帝国的梦想变为现实。因此,他征服了北非、意大利及西班牙部分地区,还编纂了罗马帝国的法典。查士丁尼宣称,“我们将重建过去的一切,尽管其价值现已降低到最低限度。……我们要重视罗马人的名誉,确保过去的一切以更大的规模重新回到我们的生活中来”。
材料三:查土丁尼在恢复帝国方面所做的努力是短暂且代价沉重的。他在地中海西部发动的战役使帝国的国库耗之殆尽,使巴尔干和亚洲各行省被忽略、易受攻击。他死后不到十年,一个新的蛮族部落伦巴第人,占领了意大利大部分地区。同样,在多瑙河边境,阿瓦尔人同斯拉夫和保加利亚臣民一起,进入巴尔干地区,取代拉丁化了的伊利里亚人,削弱了帝国的控制。在东部,查士丁尼统治时期。波斯人因受贿曾与拜占廷媾和;现在,他们在野心勃勃的大皇帝科斯罗埃斯二世的率领下,开始全面消灭东罗马帝国。到615年,他们已占领叙利亚、巴勒斯坦和埃及,并在君士坦丁堡对面的博斯普鲁斯海峡沿岸安营扎寨。    
——以上三则材料均选自《全球通史》
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同类题5

阅读理解

    Everybody hates it, but everybody does it. A recent report said that 40%of Americans hate tipping. In America alone, tipping is a $ 16 billion-a-year industry. Consumers acting politely ought not to pay more than they have to for a given service. Tips should not exist. So why do they? The common opinion in the past was that tips both rewarded the efforts of good service and reduced uncomfortable feelings of inequality. And also, tipping makes for closer relations. It went without saying that the better the service, the bigger the tip.

    But according to a new research from Cornell University, tips no longer serve any useful function. The paper analyzes numbers they got from 2,547 groups dining at 20 different restaurants. The connection between larger tips and better service was very weak. Only a tiny part of the size of the tip had anything to do with the quality of service.

    Tipping is better explained, by culture than by the money people spend. In America, the custom came into being a long time ago. It is regarded as part of the accepted cost of a service. In New York restaurants, failing to tip at least 15% could well mean dissatisfaction from the customers. Hairdressers can expect to get l5%-20%, and the man who delivers your fast food $ 2. In Europe, tipping is less common. In many restaurants the amount of tip is decided by a standard service charge. In many Asian countries, tipping has never really caught on at all. Only a few have really taken to tipping. According to Michael Lynn, the Cornell papers' author, countries in which people are more social or outgoing tend to tip more. Tipping may reduce anxiety about being served by strangers. And Mr. Lynn says, “In America, where people are expressive and eager to mix up with others, tipping is about social approval. If you tip badly, people think less of you. Tipping well is a chance to show off.”