第11题: [单项选择]双向限幅器就是()。 A. 将正信号和负信号都限幅掉 B. 上限幅器和下限幅器联用 C. 既可当上限幅器用,又可当下限幅器用 D. 对信号进行一次限幅后再进行第二次限幅 参考答案:B
第12题: [单项选择]Questions 11 to 18 are based on the conversation you have just heard. A. She thinks a hairdryer is suitable. B. She wants to know what’s making all the noise. C. She isn’t sure how practical the man’s gift is. D. She can’t hear anything when the hairdryer is on. 参考答案:A 答案解析:[听力原文] M: I’d like to get my sister a nice practical gift for her birthday. Do you have any posit