题目

下列物质的水溶液因水解而显酸性的是 A. Na2CO3               B. NaHSO4               C. NH4Cl                D. NaOH 答案：【答案】C 【解析】 【分析】 物质的水溶液因水解而显酸性，则为强酸弱碱盐； 【详解】A.碳酸钠为强碱弱酸盐，碳酸根水解使溶液呈碱性，A错误； B.硫酸氢钠是强酸酸式盐，在水中电离产生氢离子，使溶液呈酸性，B错误； C.氯化铵为强酸弱碱盐，铵根水解导致水溶液呈酸性，C正确； D.氢氧化钠为强If someone says to you “give me five”, don’t give five yuan to him! It will make others laugh! The person is not ask for your money, but your fingers.In the USA, “give me five” or “give me the high five” is a good gesture. You can often see it in films or on TV. It means the slapping(拍打) of each other’s right hands together. People do it when something happy happens. For example, if a student get an “A” in the exam or gets No.1 in the school sports meeting, he will give the high five to his friends to celebrate.Who did this gesture first? Why did he do that? It may come from the old Roman gesture of putting up the right arm for the emperor(皇帝). This showed that the person putting up his arm had nothing in his hand and he couldn’t hurt the emperor.Why not try to give the high five to your friends?1.When one of your friends asks you to give him five, you can .A. give him five yuanB. give him your handsC. slap his right hand2.What’s the Chinese meaning of the underl ined word “gesture” in the second paragraph?A. 节奏 B. 场所 C. 手势3.Now you can do “give me five” to your friends because you will .A celebrate your friends’ successB. have the same idea with your friendsC. laugh at your friend’s bad manners4.The gesture started in .A. Rome B. China C. America5.The Romans p ut up the right arms for the emperor to show that they .A. liked him very muchB. were happy to see himC. were safe for him