第3题: [单项选择]有关光纤通信光源,下列说法正确的是() A. 红外线发光二极管一般作为低速、长距离光波传输系统的光源; B. 红外线发光二极管比激光二极管结构复杂、成本高; C. 激光二极管不适合用作单模式光纤传输线的光源; D. 激光二极管适合作为高速、长距离光纤通信系统的光源。 参考答案:D
第11题: [单项选择]Why doesn’ t the customer try on that jacket A. Because he likes the jacket. B. Because he doesn’t like the color. C. Because he wants a fur coat. D. Because he wants a new suit. 参考答案:B 答案解析:[听力原文] W: Would you like to try on that jacket, Sir M: Thank you , but I think the color of t