在做俯卧撑时收紧胸部肌肉，以充分激活它们。

___Tighten your chest muscles during push-ups to engage them fully.

他用螺丝刀拧紧螺丝。

He uses a screwdriver to ___tighten the screw.

学校决定加强考试纪律。

The school decided to ___tighten the exam rules.

随着法规的调整，贷款审批标准将会收紧。

As regulations change, loan approval standards will ___tighten.