A. It is easily expanded. B. It is naturally prevalent. C. It is regenerative. D. It can be exchanged in business dealings. 参考答案:D 答案解析:[解析]事实细节题。第二段提到“it can be shared only,not exchanged in transactions”(信息只可以共享,但不会在交易中发生交换),由此可知D)项不是信
第20题: [单项选择]高原现象出现在练习的哪个阶段?() A. 开始阶段 B. 中期阶段 C. 后期阶段 D. 完成阶段 参考答案:B
第21题: [单项选择]The local authorities will take measures to deal with noise pollution in the are() A. control B. learning C. power D. government 参考答案:D 答案解析: