问题 填空题

现有四种物质①二氧化碳 ②生石灰 ③酒精 ④稀盐酸.请按照下列要求选用物质的序号填空:

(1)可用于灭火的是      

(2)实验室常用的燃料是      

(3)可作为食品干燥剂的是      

(4)用于除去钢筋表面上铁锈的是   

答案

(1)①     (2)③     (3)②      (4)④

题目分析:(1)二氧化碳的固体干冰,可以进行人工降雨,也可以做制冷剂,故答案为:①

(2)酒精是实验室常用的燃料,故答案为:③

(3)常用的干燥剂有:浓硫酸、生石灰、氢氧化钠固体等,但是可作为食品干燥剂的是生石灰,故答案为:②

(4)稀盐酸、稀硫酸都能用于金属制品表面的除锈,故答案为:④

点评:本考点考查了常见物质的性质与用途,初中阶段常见的物质的性质和用途要记牢.本题体现了:性质决定用途,用途又反映性质的理念,本考点经常出现在选择题和填空题中.

填空题
阅读理解

There is some unwelcome news for students preparing for exams and officers putting in long hours-----you don't need the break as much as you may think that makes you feel less tired.

Scientists have long assumed that willpower (意志力) is a limited resource, which is why you feel the need to have a rest, have a snack and come back to a task when you're feeling better. They argued that the only way to restore willpower was by rest, food or entertainment.

But psychologists have challenged this theory, saying weak willpower is all in your head. They found that people's beliefs in willpower determine how long and how well they'll be able to work on a tough mental exercise. "If you think of willpower as something that's limited, you're more likely to be tired when you perform a difficult task," said Prof.Veronika Job. "'But if you think of willpower as something that is not easily used up, you can go on and on."

The researchers designed four experiments to test students'-beliefs in willpower. After a tiring task, those, who believed or were led to believe that willpower is a limited resource, performed worse on standard concentration tests than those who thought of willpower as something they had more control over. They also found that leading up to final exam week, students who believed the limited resource theory ate junk food 24 percent more often than those who believed they had more control in resisting temptation (诱惑).

Mr. Job said. "The theory that willpower is a limited resource is interesting, but it has had unintended consequences. Students who may already have trouble studying are being told that their power of concentration is limited, and they need to take frequent breaks. But a belief in willpower as a non-limited resource makes people stronger in their ability to work through challenges.'"

The findings could help people who are" battling temptation. Willpower isn't driven by a biologically based process as much as we used to think. The belief in it is what influences your behavior.

小题1:The theory that willpower is limited supports that _________.

A.people must eat snacks when they feel tired

B.people do need a break to restore their willpower

C.there’s no way to strengthen people’s willpower

D.weak willpower doesn’t affect people’s life much小题2:What have the scientists long believed regarding willpower?

A.It is in the charge of people.

B.It is a limited resource.

C.There is no way to restore willpower.

D.It doesn’t easily run out.小题3:Which of the following best helps the students to prepare better for their exams?

A.Push themselves even if they want to take a break.

B.Don’t eat fast food while studying.

C.Remind themselves willpower is not limited.

D.Stay in a comfortable and quiet place.小题4:The following groups can benefit from the findings except

A.patients following strict diets

B.children liking to watch TV

C.smokers trying to give up smoking

D.employees facing a new but well-paid task小题5:What’s the best title for the passage?

A.A new theory about willpower

B.How to build strong willpower

C.The great influence of willpower

D.Willpower doesn’t last long