问题 选择题

河流阶地是常见的河流地貌之一,是由河流作用形成的沿河分布的阶梯状地形。河流阶地主要由阶地面和阶地斜坡(坡坎)两个形态要素组成(如图)。构造运动的稳定期河流以侧蚀作用为主,造成宽阔的谷底或平原。构造运动的上升期河流下切,原来的谷底或平原被抬升成为阶地面。如果这一过程多次反复,在河谷的横剖面上便可出现多级阶地。读图,回答1—2题。

1、关于构造运动形成阶地的叙述,正确的是[ ]

A.构造运动的稳定期河流以下蚀作用为主

B.构造运动的稳定期河流以侧蚀和堆积作用为主

C.构造运动的上升期河流以侧蚀和堆积作用为主

D.构造运动的上升期河流首先在上游快速下切形成阶地

2、气候变化影响河流的水量和含沙量,从而导致河水对河床产生的作用力不一样,这种因气候变化而形成的阶地称为气候阶地。在气候十分寒冷或干旱时期,流域内植被稀疏,风化强烈,碎屑物质丰富;在气候转为温暖湿润时期,流域内植被茂密。则
[ ]

A.在气候十分寒冷或干旱时期,河流以侵蚀作用为主

B.在气候十分寒冷或干旱时期,河流易形成坡坎

C.在气候转为温暖湿润时期,河床以下切侵蚀为主

D.在气候转为温暖湿润时期,河流不易形成阶地

答案

1、B

2、C

单项选择题
阅读理解

In the United States, 30 percent of the people have a “weight problem”. To many people the cause is obvious (明显的): they eat too much. But scientific evidence (证据) does little to support this idea. Going back to America of 1910, we find that people were thinner than today, yet they ate more food. In those days people worked harder physically, walked more, used machines much less, and didn’t watch television.

Several modern studies, moreover, have shown that fatter people don’t eat more on average than thinner people. A 1979 study of 3,545 London office workers showed that fat people eat less than slim (苗条的) people.

Studies also show that slim people are more active than fat people. A study by a research group at Stanford University found the following interesting facts:

The more the man ran, the greater loss of the body fat.

The more they ran, the greater increase in food intake.

Thus, those who ran the most ate the most, yet lost the greatest amount of body fat.

小题1: Nowadays many Americans have the problem that ______.

A.they are too slim

B.they work too hard

C.they are too fat

D.they lose too much body fat小题2: According to the passage, how many people in 900 Americans have a “weight problem”?

A.150.

B.300.

C.600.

D.270.小题3:Is there any scientific evidence to support the idea that eating too much is the cause of a “weight problem”?

A.Yes, there is plenty of evidence.

B.Of course, there is some evidence to support this.

C.There is hardly any scientific evidence to support this.

D.We are not sure.小题4:The Americans in 1910 ________.

A.ate more food and had more physical activities

B.ate less food but had more physical activities

C.ate less food and had less physical activities

D.had more problems