问题 选择题

某液体若是溶液,其必然是(  )

A.长期敞口放置不会析出沉淀

B.一种固体溶解在一种液体里

C.只由一种溶质和一种溶剂混合后形成的均一稳定的混合物

D.至少由两种物质组成的均一稳定的混合物

答案

A、溶液尽管具有稳定性,但长期敞口放置,水分会蒸发,也会析出沉淀;故选项说法错误;

B、C、由溶液的概念可知,溶液中的溶质可以是一种或是多种,故选项说法错误;

D、溶液是均一的、稳定的混合物,所以溶液是至少由两种物质组成的均一稳定的混合物,故选项说法正确;

故选D.

单项选择题
阅读理解

Getting rid of dirt, in the opinion of most people, is a good thing. However, there is nothing fixed about attitudes to dirt.

In the early 16th century, people thought that dirt on the skin was a means to block out disease, as medical opinion had it that washing off dirt with hot water could open up the skin and let ills in. A particular danger was thought to lie in public baths. By 1538, the French king had closed the bath houses in his kingdom. So did the king of England in 1546. Thus began a long time when the rich and the poor in Europe lived with dirt in a friendly way. Henry IV, King of France, was famously dirty. Upon learning that a nobleman had taken a bath, the king ordered that, to avoid the attack of disease, the nobleman should not go out.

Though the belief in the merit of dirt was long-lived, dirt has no longer been regarded as a nice neighbor ever since the 18th century. Scientifically speaking, cleaning away dirt is good to health. Clean water supply and hand washing are practical means of preventing disease. Yet, it seems that standards of cleanliness have moved beyond science since World War Ⅱ. Advertisements repeatedly sell the idea; clothes need to be whiter than white, cloths ever softer, surfaces to shine. Has the hate for dirt, however, gone too far?

Attitudes to dirt still differ hugely nowadays. Many first-time parents nervously try to warn their children off touching dirt, which might be responsible for the spread of disease. On the contrary, Mary Ruebush, an American immunologist(免疫学家),encourages children to play in the dirt to build up a strong immune system. And the latter position is gaining some ground.

小题1:The kings of France and England in the 16th century closed bath houses because        .

A.they lived healthily in a dirty environment.

B.they thought bath houses were to dirty to stay in

C.they believed disease could be spread in public baths

D.they considered bathing as the cause of skin disease小题2:Which of the following best describes Henry IV’s attitude to bathing?

A.Afraid.

B.Curious.

C.Approving.

D.Uninterested.小题3:How does the passage mainly develop?

A.By providing examples.

B.By making comparisons.

C.By following the order of time.

D.By following the order of importance.小题4:What is the author’s purpose in writing the passage?

A.To stress the role of dirt.

B.To introduce the history of dirt.

C.To call attention to the danger of dirt.

D.To present the change of views on dirt.