【单选题】把 2- 丁烯与跟溴水作用,其产物主要是( )。
【单选题】It's so noisy. I'd really appreciate ______ if you'd turn the radio down. [ ]
【单选题】— I didn't hear you come in last night. — That's good. We tried ______ noisy. [ ]
【单选题】Please ( ) the radio, it’s noisy.
【简答题】矩形波导不能传输()波,只能传输()波和()波。当a>b时,截止频率最低的模式为()模,相应的截止波长为()。
【判断题】在矩形波导只能传输TE波模和TM波模的电磁波。( )