问题 选择题

下列有关物质的性质或应用说法正确的是

A.二氧化硫可用来加工食品,使食品增白

B.SiO2既能溶于NaOH溶液又能溶于HF,说明SiO2是两性氧化物

C.蛋白质水解生成葡萄糖放出热量,提供生命活动的能量

D.锅炉水垢中含有的CaSO4,可先用Na2CO3溶液处理,后用酸除去

答案

答案:D

题目分析:SO2有毒,不能用来加工食品,使食品增白,A不正确;二氧化硅是酸性氧化物,B不正确;蛋白质水解生成氨基酸,C不正确;碳酸钠能和硫酸钙反应生成更难溶碳酸钙,然后用酸溶解碳酸钙,即可除去,D正确,答案选D。

点评:该题是常识性知识的考查,试题紧扣教材,基础性强,旨在培养学生灵活运用基础知识解决实际问题的能力,难度不大。

单项选择题

In the 1960s, medical researchers Thomas Holmes and Richard Rahe developed a checklist of stressful events. They appreciated the tricky point that any major change can be stressful. Negative events like "serious illness of a family member" were high on the list, but so were some positive life-changing events, like marriage. When you take the Holmes-Rahe test you must remember that the score does not reflect how you deal with stress—it only shows how much you have to deal with. And we now know that the way you handle these events dramatically affects your chances of staying healthy.

By the early 1970s, hundreds of similar studies had followed Holmes and Rahe. And millions of Americans who work and live under stress worried over the reports. Somehow, the research got boiled down to a memorable message. Women’s magazines ran headlines like "Stress causes illness. " If you want to stay physically and mentally healthy, the articles said, avoid stressful events.

But such simplistic advice is impossible to follow. Even if stressful events are dangerous, many—like the death of a loved one—are impossible to avoid. Moreover, any warning to avoid all stressful events is a prescription (处方)for staying away from opportunities as well as trouble. Since any change can be stressful, a person who wanted to be completely free of stress would never marry, have a child, take a new job or move.

The notion that all stress makes you sick also ignores a lot of what we know about people. It assumes we’re all vulnerable (脆弱的) and passive in the face of adversity (逆境). But what about human initiative and creativity Many come through periods of stress with more physical and mental vigor than they had before. We also know that a long time without change or challenge can lead to boredom, and physical and mental strain.

According to the passage people who have experienced ups and downs may become ().

A. nervous when faced with difficulties

B. physically and mentally strained

C. more capable of coping with adversity

D. indifferent toward what happens to them

问答题 简答题