第14题: [单项选择]Passage Two Questions 29 to 31 are based on the passage you have just heard. A. To lower their exchange rates. B. To regulate their exchange rates. C. To raise their regulated rates. D. To make no change of their rates. 参考答案:B 答案解析:[听力原文] What did countries that signed the agreement promise to do
第27题: [单项选择]8255A的PA口工作于方式2时,PB口可以工作于( ) A. 方式0的无条件传送和方式1 B. 方式0的查询传送和方式1 C. 方式2 D. 任何方式 参考答案:A 答案解析:[解析] 方式2只限于A组使用,它用A口得8位数据线,用C口的5位进行联络。工作时输入、输出数据都能锁存。当A组在方式2下工作时,B组可以在方式0(此时只能采用无条件传送)或方式1工作。