题目

在光合作用实验里，如果所用的水中有0.20％的水分子含18O，那么，植物进行光合作用释放的氧气中，含18O的比例为 A.0.20％               B.0.44％               C.0.64％                      D.0.88％ 答案：A 解析: 根据同位素示踪实验结果可知，光合作用过程中释放的氧气全部来自参加反应的水，因此，供给光合作用的水中有0.20％的水分子含18O，那么，光合作用所释放的氧气中，含18O的比例还是0.20％。Bike-sharing is a new choice for short journeys in cities. It is good to the ______ development of the big cities.A ______ by a company found that shared bikes started the nation’s ______ for bikes again. Now more and more Chinese people are ______ bikes instead of cars to make short journeys in cities.An engineer of that company says that since the ______ of shared bikes, people have made fewer trips by car. The love for shared bikes is not only among ______ people, who were born in the 1980s and 1990s, but also among people over sixty.At weekends, the number of the riders in Shenzhen reaches the ______ of all cities. On weekdays, the number of people who use shared bikes to travel to work is ______ in Shanghai.It is said that bike-sharing will help ______ the cities’ environment. It not only helps solve the traffic problems, but also will help to make more use of ______ in cities. Take Beijing as an example if more people choose shared bikes, an area of five Bird’s Nest stadiums (体育场)will be saved.1.A. slow B. healthy C. harmful D. sudden2.A. rule B. plan C. report D. suggestion3.A. search B. worry C. preparation D. love4.A. choosing B. pushing C. repairing D. locking5.A. end B. start C. control D. fall6.A. strong B. weak C. old D. young7.A. top B. side C. corner D. line8.A. coming over B. putting off C. going up D. giving away9.A. discover B. separate C. experience D. improve10.A. air B. time C. space D. money 1.B 2.C 3.D 4.A 5.B 6.D 7.A 8.C 9.D 10.C 【解析】试题分析：这篇短文主要介绍了新兴事物———共享单车。共享单车的出现有助于城市健康发展，在大城市越来越多的人喜欢上共享单车。 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.