His hold on her arm tightened.

他把她的胳膊抓得更紧了。

She tightened her grip on his arm.

她抓他的手臂抓得更紧了。

She tightened her belt an extra notch.

她将腰带又束紧了一格。

Her arms tightened about his neck in gratitude.

她的双臂紧紧搂住他的脖子，充满感激。

The nuts weren't properly tightened and the wheel came off.

螺母没拧紧，轮子脱落了。