题目

下列化学用语正确的是（   ） A. 某烷烃的命名为：2-甲基-3-乙基丁烷          B. 羟基的电子式为： C. 丙烷分子的球棍模型:             D. 丙酸的键线式: 答案：C 【解析】 A. 主链选择错误，应该为2，3-二甲基戊烷 ，错误；B. 羟基的电子式为，错误；C. 丙烷的分子式为C3H8，球棍模型为，正确；D. 丙酸中含有羧基，中含有酯基，没有羧基，错误；故选C。 点睛：本题考查了常见化学用语的判断。比例模型、球棍模型要能体现原子的相对大小及分子的空间结构。本Many foreign people may want to travel to China. But when is the best time to visit some of Chinese cities? Here is some advice.The best time to visit Beijing is in September or October, because it’s cool in these months. There are many old and great places to visit, such as the Great Wall, the Summer Palace and the Palace Museum. People may also visit some new places like the Bird Nest and the Water Cube.Do you want to feel cool in a hot summer? Please go to Lhasa. And the best time to visit it is in July or August. The city lies in the plateau that is usually thousands of metres above the sea level and the weather is pretty cool in summer. There you may enjoy special dance and music and taste good food. But you might need a coat or sweater because it’s cold in the evening.In most places of China, it’s usually cold in winter. But Hainan Island is different. In winter, it’s always warm there. So winter is the best time to visit Haikou and Sanya. There you’ll probably enjoy swimming, diving or walking on the beach. Of course, you may taste all kinds of fruit and seafood there. That’s great!1.How many Chinese cities does the passage tell us?A. One. B. Two. C. Three. D. Four.2.When is the best time to visit Beijing?A. In spring. B. In summer. C. In autumn. D. In winter.3.What might the underlined word “plateau” mean in Chinese?A. 丘陵 B. 高原 C. 盆地 D. 平原4.What’s the main idea of the passage?A. It’s best to visit Chinese cities in different times.B. All the foreign people love to visit Chinese cities.C. There are many great cities in China for people to visit.D. In China, people should visit some cities in summer or winter.