他的手紧紧抓住了她的胳膊。

His hand ___tightened around her arm.

系紧带子，这样它们就不会摩擦了。

___Tighten the straps so they don't rub.

他越是挣扎，绳子就勒得越紧。

As he struggled, the ropes ___tightened even more.