题目

物质的性质决定物质的用途．按要求从氧气、氢气、盐酸、氯化钠、浓硫酸、水、氢氧化钠中选择合适的物质，将其化学式填写在下列空格中． （1）可以燃烧的气体 ； （2）最常用的溶剂 ； （3）可做干燥剂的酸 ； （4）常做调味品的盐 ． 答案：分析：首先根据题意确定物质的化学名称，然后根据书写化学式的方法和步骤写出物质的化学式即可． 解答：解：（1）氢气具有可燃性，是可以燃烧的气体，其化学式为：H2． （2）水是最常用的溶剂，其化学式为：H2O． （3）浓硫酸具有吸水性，是可做干燥剂的酸，其化学式为：H2SO4． （4）氯化钠是Tea is an important part of Chinese tradition. Tea has very close relationship to Chinese culture.It is said that Chinese tea was discovered by King Shen Nong. People say that he lived 5，000 years ago. One summer day, while he was visiting a faraway part of his country, he felt very thirsty. The servants began to make water hot enough to turn into gas for him to drink. Dried leaves from a near plant fell into the water. The king drank some, and found it could make him feel less tired. Also as a scientist, Shen Nong was interested in the new drink. And so, tea was created in 2737 BC.Drinking tea has many advantages. It makes people feel less tired, clears heat inside the human body and helps people lose weight. As you add a cup of tea to your daily life, please check the following helpful advice.•Drink it hot. Tea oxidizes(氧化) quickly, so it is suggested that you drink it hot.•Do not drink too much strong tea. It will probably be harmful to your stomach and make you feel sick if you make the tea too strong.•The best time to drink tea is between meals. It may not make you have a strong wish to eat when your stomach is empty, or cause stomachache when your stomach is full.•Do not drink with medicine. It may change the medical result. You can drink tea two hours after you take medicine.•Green tea is the best choice for office workers.Why? Because green tea helps stop the bad result of the computer.1.Paragraph 2 is mainly about ______.A. when King Shen Nong livedB. where Chinese tea was createdC. how Chinese tea was discoveredD. why King Shen Nong drank tea2.Drinking tea has lots of advantages EXCEPT ______.A. helping you lose weightB. letting you feel less tiredC. having a strong wish for foodD. clearing heat inside your body3.Mr. Smith is a computer teacher. He'd better drink ______.A. green tea B. black teaC. strong tea D. coffee with milk4.What can we infer(推断) from the passage？A. Don't drink too much strong tea.B. Not all office workers drink green tea.C. Tea is connected with Chinese culture closely.D. King Shen Nong loved creating new things.5.The passage is mainly written to ______.A. let us know how tea was discoveredB. give some advice about drinking teaC. tell people the history of teaD. advise people to drink green tea