knock under的用法和样例：
例句
用作及物动词 (vt.)
- His army never came under the yoke of invaders.
他的军队从来不向侵略者屈服。 - Tom did not knuckle down under the attacks.
面对这些攻击，汤姆并没有屈服。
词汇搭配
- knock the sand from under someone 推翻某人的打算...
