他弯下腰去系鞋带。

He was ___stooping to tie his shoelaces.

她绝不会委屈自己去参与这种卑劣的勾当。

She would never ___stoop to participating in such despicable acts.

那位著名教授屈尊回答了学生的简单问题。

The famous professor ___stooped to answer the student's simple question.