lie behind
US /laɪ bɪˈhaɪnd/
UK /laɪ bɪˈhaɪnd/

1.
隐藏在背后, 是...的原因
to be the real reason or explanation for something
:
•
The true motives lie behind his sudden resignation.
他突然辞职的真正动机隐藏在背后。
•
What lies behind their decision to move?
他们搬家的决定背后是什么?