他在出发前检查并拧紧了自行车上的所有螺丝。

He checked and ___tightened all the screws on his bike before the trip.

学校最近加强了考勤规定。

The school recently ___tightened its attendance rules.

当截止日期临近时，她的肩膀明显绷紧了。

Her shoulders visibly ___tighten as the deadline approaches.

她拧紧螺丝，确保架子稳固。

She ___tightens the screws to make sure the shelf is secure.