hum
劍橋詞典
hum verb (MAKE A NOISE)
[ 不及物動詞：后面不接賓語的動詞 ]to make a continuous low sound
發(fā)出連續(xù)低沉的聲音，嗡嗡作響
The computers were humming in the background . 計算機在背景中嗡嗡作響。
What's that strange humming sound ? 那種奇怪的嗡嗡聲是什么？
[ 不及物動詞：后面不接賓語的動詞 or 及物動詞：后面接賓語的動詞 ]
to sing without opening your mouth
哼（曲子）
She hummed to herself as she walked to school . 她在上學(xué)的路上邊走邊哼曲子。
I've forgotten how that song goes - could you hum it for me? 我忘了那個調(diào)子怎么唱了——你能給我哼一下嗎？
[ 不及物動詞：后面不接賓語的動詞 ] informal
to be busy and full of activity , excitement , sounds , or voices
忙亂，忙碌；嘈雜
The bar was really humming last night . 昨晚酒吧里一片亂哄哄的。