第3题: [单项选择]关于管电压、管电流的叙述,正确的是 A. 管电压是有效值、管电流是平均值 B. 管电压是峰值、管电流是有效值 C. 管电压是峰值、管电流是平均值 D. 管电压是峰值、管电流是峰值 E. 管电压是平均值、管电流是有效值 参考答案:C 答案解析:X线管两极的管电压是峰值,管电流是平均值。
第32题: [单项选择]Which book has the man’s brother got A. He had to work overtime. B. His car ran out of gas. C. He was held up in traffic. D. He had a traffic accident. 参考答案:C 答案解析:[听力原文] M: If the traffic wasn’t so bad, I could have been home by 6:00. W: What a pity! John w