muhi-frequency的用法和樣例：
例句
- An underwater acoustic communication scheme using time delay and multiple frequency modula-tion technique is presented in this paper.
研究了一種採用脈衝時延差和多頻碼元組合編碼的水聲通信技術。 - While single frequency tones worked on certain phone routes, the most common signaling on the then long distance network used Multi-Frequency tones.
而某些單頻音調閃耀電話線最常見的則長途信令網採用多頻音調。
