Correct

不绝如缕

/ bùjué rú lǚ /
Strokes

Definition

hanging by a thread/very precarious/almost extinct/(of sound) linger on faintly

Example

Definition

(of situation) hanging by a thread; very precarious

1
jiā
他家
dài
dānchuán
单传
  
,
jué
不绝如缕
  

There has been only one son in his family for generations, making the family/male line precarious.

Definition

(of sound or voice) lingering on faintly

2
men
他们
de
shēng
歌声
jué
不绝如缕
  
,
huídàng
回荡
zài
shān
山谷
zhōng
  

Their singing lingered on faintly in the valley.