红外通信是利用 作为传递信息的媒体作为通信信道

nB–Mny boy students think mth is _____ English. --Igree. I’m wek in English.much difficult thn B．so difficults C．less difficult thn D．more difficult thnA．much difficult thanB．so difficult asC．less difficult thanD．more difficult than

A．much difficult thanB．so difficult asC．less difficult thanD．more difficult than