I don't know what to make of the new manager.
這位新經理，我不知道怎么評價他才好。
These problems are all in your mind, you know.
你知道，這些問題都只是你的憑空想象而已。
Some people don't know when they're well off.
有些人身在福中不知福。
Children can be difficult as we know only too well.
小孩子往往很難對付，對此我們都非常清楚。
There were a whole lot of people I didn't know.
有許多人我都不認識。