题干

下列有关说法正确的是(    )

A:蛋白质和油脂都属于高分子化合物,一定条件下都能水解

B:医疗上可用硫酸钡作x射线透视肠胃的内服药,是因为硫酸钡不溶于水

C:用过滤的方法从碘的四氯化碳溶液中获得碘

D:用浓硫酸配制一定物质的量浓度的稀硫酸时,浓硫酸溶于水后,应冷却至室温才能转移到容量瓶中

上一题 下一题 0.0难度 选择题 更新时间:2020-04-08 09:56:53

答案(点此获取答案解析)

D

同类题4

根据短文内容的理解,选择正确答案。   

    When you cough or sneeze, you'd better turn your head away from others and cover your mouth with the full part of your hand. And then, you should say, "Excuse me."

    This seems so simple, but it is surprising how many kids have never been told to do this. Actually, I notice adults all the time who cough and sneeze in public without placing a hand over the mouth. One important thing I point out to the kids is that after they sneeze or cough on their hands, they should wash their hands as soon as possible. If not, they will be passing those germs (细菌) along to everything and everyone they touch.

 

    If you come to a door and someone is following you, hold the door. If the door opens by pulling, pull it open, stand to the side, and allow the other person to pass through first, then you can walk through. If the door opens by pushing, hold the door after you pass through.

    After a few weeks of seeing kids try to get through doors in the school and watching them enter restaurants as the door hit other people, I knew I had to discuss the problem with my students. Teaching them small acts of kindness, such as letting someone else go through a door first as they hold it open, may seem unimportant, but it can go along way toward helping students realize how to be polite and thank others. Once they've been told, they're halfway there.

    When we have to go up moving stairs, we will stand to the right. That will give others who are in a hurry a choice of walking up the left-hand side of the moving stairs. When we are going to enter a lift, the underground, or a doorway, we will wait for others to exit before we enter.

    After college when I moved to London, I was surprised at how polite everyone was in the subways. I was even more touched when I traveled to Japan. In both places, people made efforts to make way for others. On moving stairs, everyone stood to the right and walked to the left. On lifts, everyone would stand over to the side and allow others to exit before they would begin to enter.