等到四下无人，他便从窗户爬了进去。

As soon as the coast was clear he climbed in through the window.

《牛津词典》

一见钟情爱上你，二话不说抱住你，三天两头来找你，四下无人亲亲你，五天之内娶到你，六十年内不分离！

Fall in love with you, hug you without demur, every two or three days to come to you, four no kiss you marry to you within five days, not separate for sixty years!

youdao

在我前方的路面上，狗在阳光下打盹，孩子们则在柏油已经碎裂的空旷道路上跑来跑去，除了他们之外四下无人。

Up the pavement ahead of me, dogs doze in the sun as children run backforth across the otherwise empty road's chipped asphalt.

youdao