after a brief good night
Does this mean the same thing as "after merely saying 'good night'"?
Yes, that's right
When, at night, people reach the place where they are going to part, they may stand around talking for a while
Or they may just say "goodnight" and then go - that's a brief goodnight
So far as I can see, you can write goodnight or good-night or good night. They are all OK
People are waiting to help.
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