catch sight of

To see someone or something very briefly or suddenly.

突然地，粗略地看到某人或某物

I didn't so much as catch sight of him all day long.

我一整天都没见他人影。

I walked slowly, casually, hoping she would catch sight of me.

我装作满不在乎地款款而行，希望她会一眼看到我。

Keep looking up, and you may catch sight of some unexpected creatures.

继续观察下去，说不定会看到意想不到的动物。