PHRASAL VERB 屈服；认输 If you knuckle under, you do what someone else tells you to do or what a situation forces you to do, because you realize that you have no choice. 屈服；认输 [informal]
It is arguable whether the rebels will knuckle under. [VERBPREP.]
还不能确定反叛者是否会投降。
The United States, he said, did not knuckle under to demands. [VERBPREP. + to]