由于天气恶劣，他们不得不返回。

They had to ___turn ___back because of the bad weather.

我们走着走着遇到一条过不去的河，所以我们就返回了。

As we were walking along we came across a river we couldn't pass, so we ___turned ___back.

由于道路封闭，我们不得不把车开回去。

Due to the road closure, we had to ___turn the car ___back.