题目

右下图是两个生态系统中腐殖质总量随时间而发生变化的情况，这是指哪两个生态系统？ A  热带草原    热带雨林    B  热带雨林    温带阔叶林 C  冻土苔原    热带雨林    D  热带草原    温带草原 答案：C 解析: C正确：因为冻土苔原位于地球最冷的北极地区，而热带雨林位于地球最热的赤道地区。两地生态系统腐殖质的积累速度相差最大，热带雨林腐殖质的积累只需短时间便能达到最大值，这正如曲线Ⅱ所表示的那样，而冻土苔原腐殖质的积累则需经历漫长的时间才能达到最大值，正如曲线Ⅰ所表示完形填空。As we all know, Chinese students are hard-working. But they’re _______at the same time.At school, they have to follow the strict school _______ . For example, they _______ have long hair or wear strange (奇怪的) clothes.And at home, they’re always busy with their homework and they don’t have any free time to do what they like. Once (一旦) they don’t do well in exams, their parents will lose _______ for them.On weekends, their parents tell them to take part in different classes they don’t like. They always feel _______ and bored. They _______ interest in school things slowly. Some students can’t _______ it and leave home. Because their parents only care about children’s study and they never _______ what they want.“Many students can do nothing _______ study. Some students even don’t know _______ to get on well with others and how to take care of others,”said an expert (专家).“This is a serious problem. It’s necessary for us to think it over and solve it well,”said another expert.【1】A. glad B. unhappy C. kind D. healthy【2】A. time B. teachers C. rules D. classmates【3】A. mustn’t B. can’t C. shouldn’t D. may not【4】A. future B. home C. school D. hope【5】A. excited B. tired C. active D. sad【6】A. lose B. show C. have D. take【7】A. believe B. stand C. love D. wonder【8】A. mind B. tell C. talk D. call【9A. with B. without C. in D. except【10】A. where B. how C. why D. whether