眉头展开用英文怎么说？

眉头展开 knitted brows

问题解决了，老人家紧锁的眉头也舒展了。
Once the problem was solved, the old man's knitted brows became smooth again

with brows relaxed 眉头展开
with brows raised,眉头紧缩

unbend one's brows

Unfold the brows.

release/relax the brows