adj.发嗡嗡声的；声音低沉单调的
动词drone的现在分词形式.
Airplanes kept on droning in the distance throughout the night. 整个夜晚，远处的飞机隆隆地响个不停。
A droning, mechanical delivery of the speech. 一篇低沉单调、呆板的演说
