sing, hum

名詞 hum:

1. the state of being or appearing to be actively engaged in an activity
   同義詞：busyness
2. an Islamic fundamentalist group in Pakistan that fought the Soviet Union in Afghanistan in the 1980s; now operates as a terrorist organization primarily in Kashmir and seeks Kashmir's accession by Pakistan
   同義詞：Harkat-ul-Mujahidin, Harkat ul-Ansar, HUA, Harkat ul-Mujahedeen, Al Faran, Movement of Holy Warriors
3. a humming noise
   同義詞：humming

動詞 hum:

1. sing with closed lips
2. be noisy with activity
   同義詞：buzz, seethe
3. sound with a monotonous hum
   同義詞：thrum
4. make a low continuous sound

1. His strong voice cut through the hum of conversation like a knife through butter.
   他那宏亮有力的聲音一下子壓倒了嗡嗡的談話聲。
2. Hum the opening bars of your favourite tune.
   哼一哼你喜愛的曲子的開頭幾個小節(jié)。
3. Hum, you're joking!
   哼，你在開玩笑吧！
4. She was humming to herself.
   她獨自哼著歌。
5. She continued to hum the song over and over.
   她一遍又一遍地不斷哼唱那支歌。
6. The only sound he heard was the hum of the machine.
   他聽到的唯一的聲音就是那臺機器的嗡嗡聲。

hum

v.（動詞）
hummed,hum.ming,hums
v.intr.（不及物動詞）

To emit a continuous low droning sound like that of the speech sound (m) when prolonged.
嗡嗡聲，哼哼聲：發(fā)出一種持續(xù)、低沉的嗡嗡聲，類似m被拖長后的聲音
To emit the continuous droning sound of a bee on the wing; buzz.
發(fā)嗡嗡聲：蜜蜂翅膀發(fā)出的持續(xù)的嗡嗡聲；嗡嗡聲
To give forth a low, continuous drone blended of many sounds:
發(fā)出嘈雜聲：發(fā)出各種持續(xù)、低沉、混在一起的嗡嗡聲：
例句：
The avenue hummed with traffic.
大路上的車輛發(fā)出混雜的聲音

To be in a state of busy activity.
忙碌：處于繁忙的狀態(tài)
To produce a tune without opening the lips or forming words.
哼：不張開嘴或不構(gòu)成詞而產(chǎn)生的聲調(diào)
v.tr.（及物動詞）
To sing (a tune) without opening the lips or forming words.
哼唱：不張開嘴或不構(gòu)成詞而唱（曲調(diào)）
n.（名詞）
The sound produced by humming.
嗡嗡聲：哼出來的聲音
The act of humming.
哼唱的動作
interj.（感嘆詞）
Used to indicate hesitation, surprise, or displeasure.
發(fā)哼哼聲：用于表示猶豫，吃驚或不快

來源：
Middle English hummen
中古英語 hummen
[of imitative origin]
[源于模仿]

【引伸】
hum.mable
adj.（形容詞）
hum.mer
n.（名詞）