问题 实验题

现有一种无色的营养液,可能由KNO3、Ca(NO3)2、K2CO3、KCl中的一种或几种物质组成,为探究其成分,某同学设计并完成了如下图所示的实验。

根据以上实验,请你进行有关推断。

①由实验1可确定原营养液中一定没有的物质是________;

②根据实验1、实验2推测原营养液的组成可能有_____种情况;

③若测得原营养液中K+和Cl-的数目之比为1:1,则原营养液的组成中的溶质是________________。

答案

①K2CO3

②2

③KCl、Ca(NO3)2

阅读理解

阅读理解。

     The first breath-taking pictures of the Earth taken from space showed it as a solid ball covered by brown

land masses and blue- green oceans. We had never seen the Earth from that distance before. To us, it appeared

as though the Earth had always looked that way and always would. Scientists now know, however, that the

surface of the Earth is not as permanent as we had thought.

     Scientists explain that the surface of our planet is always moving. Continents moves about the Earth like

huge ships at sea. They float on pieces of the Earth's outer skin. New outer skin is created as melted rock

pushed up from below the ocean floor. Old outer skin is destroyed as it rolls down into the hot area and melts

again.

     Only since the 1960s have scientists really began to under- stand that the planet Earth is a great living

machine. Some experts have said this new understanding is one of the most important revolutions in scientific

thought. The revolution is based on the work of scientists who study the movement of the continents-a science

called plate tectonics.

     The modern story of plate tectonics begins with the German scientist Alfred Wegener. Before World War

One, Wegener argued that the continents had moved and were still moving. He said the idea first occurred to

him when he observed that the coastlines of South America and Africa could fit together like two pieces of a

puzzle. He proposed that the two continents might have been one and then split apart. 

     Wegener was not the first person to wonder about the shape of the continents. About 500 years ago,

explorers thought about it when they made the first maps of Americas. The explorers noted the east coast of

North America and South America would fit almost exactly into the west coast of Europe and South Africa.

What the explorers did not do, but Wegener did, was to investigate the idea that the continents move.

1. What does the writer mainly tell us in the passage?

A. The first breath-taking pictures of the Earth taken from space.

B. Human's recognition of the earth's surface.

C. The German scientist Alfred Wegener.

D. The early explorers' discovery.

2. Which of the following is true according to the passage?

A. We didn't see the Earth from far away until we saw the picture taken in the space.

B. Our ancient thought that the surface of the earth is still.

C. Alfred Wegener was not the first person to investigate the idea that the continents move.

D. The coastlines of India and Africa fit together.

3. The last word of the third paragraph "tectonics" means "____".

A. study of construction

B. study of architecture

C. earth surface

D. structural geology

单项选择题