when in Rome do as the Romans do字面意思在罗马，像罗马人一样，引申为入乡随俗。

【例句】
I always carry an umbrella when I visit London. When in Rome do as the Romans do.
我去伦敦总要带一把雨伞，入乡随俗嘛。

When in Rome, do as the Romans do and take the chance to practice your English skills.
你最好也入乡随俗，好好把握机会练习英语。