问题 单项选择题

阅读下面短文,回答下 * * 道题。
基于潮流和波浪而产生的周期性流动以外的、比较固定的水流叫洋流。海水会经历几十年甚至数百年的时间在全世界的海域中循环,洋流指的是这种地球规模的海水循环的一部分。在洋流中,有像陆地上的河流一样幅度较窄而流速快的,也有幅度无限宽广而流速缓慢的,其大小、强度不能一概而论。以代表性的洋流之一——黑潮为例,在强流带时可达到2.5米/秒的速度,水流的路径、速度随季节和年代不同都会发生很大变化。一般意义上的洋流,是在大海的表层流动(表层流),而深层的水流则较弱,速度在每秒几厘米以下,水流的结构也很复杂。
表层洋流的发生,首先是因为风。水面上一起风,由于风力作用,水层就被拖动。表层的水一动,因海水彼此之间存在摩擦力,下面的水层便接连不断地被拖动。实际上,洋流并非沿着风的方向前进。像洋流这种地球上的大规模运动通常要受到地球自转的影响,即要受到科里奥利力的作用。在北半球,运动物体所受科里奥利力在其运动方向垂直的右方起作用。这样,海水就偏离了风力作用方向的方位前进,在北半球,表层洋流沿偏离风向约四五度的右方流动。
海面并不是完全水平的,温度、盐分、海水密度等多种因素使得海面凹凸不平。笼统来说,水温高的部分密度小,水面就高,水流理应从高处向低处流,但是由于科里奥利力的作用,高处的水流沿偏右的方向流动,这称为地衡流。海水的盐分等因素也可造成海水密度不同。海水中溶入了各种各样的物质,其中钠和卤素占绝大多数。另外,也有镁、钾、钙等盐类。盐分浓度会随年蒸发量、降水量而发生变化。此外,有河流等大陆水流注入的沿岸海域盐分较少,这些都影响洋流的流向。

属于“表层洋流的发生”条件的一项是:

A.有风力作用

B.基于地球自转

C.海水自身的摩擦力

D.必须与风形成四五度的角度

答案

参考答案:D

解析:这是洋流发生后流动的角度,不是发生的条件。

阅读理解

阅读理解

     I travel a lot, and I find out different "styles" (风格) of directions every time 1 ask "How can I get to

the post office?"

     Foreign tourists are often confused (困惑) in Japan because most streets there don't have names; in

Japan, people use landmarks (地标) in their directions instead of street names. For example, the Japanese will say to travelers, "Go straight down to the corner. Turn left at the big hotel and go past a fruit market.

The post office is across from the bus stop."

     In the countryside of the American Midwest, there are not usually many landmarks. There are no

mountains, so the land is very flat; in many places there are no towns or buildings within miles. lnstead of

landmarks, people will tell you directions and distances. In Kansas or Iowa, for example, people will say, "Go north two miles. Turn east, and then go another mile."

     People in Los Angeles, California, have no idea of distance on the map; they measure distance in time, not miles. "How far away is the post office?" you ask. "Oh," they answer, "it's about five minutes from here." You say, "Yes, but how many miles away is it?" They don't know.

     It's true that a person doesn't know the answer to your question sometimes. What happens in such a

situation? A New Yorker might say, 'Sorry, I have no idea." But in Yucatan, Mexico, no one answers "I

don't know." People in Yucatan believe that "I don't know" is impolite, They usually give an answer,

often a wrong one. A tourist can get very, very lost in Yucatan!

1. When a tourist asks the Japanese the way to a certain place they usually _________

A. describe the place carefully

B. show him a map of the place

C. tell him the names of the streets

D. refer to recognizable(可辨认的) buildings and places

2. What is the place where people measure distance in time?

A. New York.  

B. Los Angeles.  

C. Kansas.  

D. Iowa.

3. People in Yucatan may give a tourist a wrong answer ________

A. in order to save time  

B. as a test 

C. so as to be polite  

D. for fun

4. What can we infer from the text?

A. It's important for travelers to understand cultural differences.

B. It's useful for travelers to know how to ask the way properly.

C. People have similar understandings of politeness.

D. New Yorkers are generally friendly to visitors.

问答题 简答题