His family is a nuclear family with three generations living together under one roof.
他的家庭是三代同堂住在同一屋檐下。
We can't make a decision without knowing the facts.
我们不能不知道事实,就作决定。
Those planning a trip to remote areas, or intending to live in countries where drinking water is not readily available, should know about the various possible methods for making water safe.