1. With his incredible saves, the goalkeeper proved to be the team's key player.
凭借他惊人的扑救，这位守门员证明自己是球队的关键人物。

2. The keystones are the central stones in an arch, which hold all the other stones in place.
关键石块是拱门中的中心石块，它们固定住其他所有的石块。

3. My coworker is always slacking off and being a keystoner on the job.
我的同事总是偷懒，成为工作中的懒汉。