由于天气恶劣，他们不得不返回。

They had to ___turn ___back because of the bad weather.

我们走着走着遇到了一条无法通过的河流，所以我们返回了。

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

警察让抗议者返回。

The police ___turned ___the ___protesters ___back.