good day

英 [ˌɡʊd ˈdeɪ]

美 [ˌɡʊd ˈdeɪ]

int. (白天见面或分手时用语)白天好，你(们)好，再见

牛津词典

exclamation

（白天见面或分手时用语）白天好，你（们）好，再见
used to say hello or goodbye politely when people first see each other or leave each other during the day
1. Good day to you.
  你好。

CONVENTION （问候用语，代替Hello及Goodbye）你（们）好，再见
People sometimes say 'Good day' instead of 'Hello' or 'Goodbye'.
1. Well, I'd better be off. Good day to you.
  好啦，我得走了，再见。

noun

Have a good day.
有一个早晨好。
Too good today, that is a good day yesterday!
过好了今天，也就是明天有了好的昨天！
I thought this might be a good day.
我觉得那会是段好日子。
You could say it was a doggone good day for this golden retriever in Washington State.
你可能会说，对这只华盛顿的金毛猎犬真是糟糕的一天，昨天晚上它坐的汽车翻到了沼泽地上。
But you said it wasn't a good day.
但你说今天不是个好日子。
Today was a good day and a bad day.
今天是一个好日子，也是一个坏日子。
Today is a good day, the rain stopped;
今天是个好日子，大雨停了；
I hope that all of you have a good day.
我希望你们都有美好的一天。
Good day! Let me introduce myself and tell you a few things about who I am.
大家好，让我来介绍一下自己，并告诉你们一些关于我的情况。
It was a good day for outdoor activities, as I had stayed at home for a period.
我在家里呆了有一段时间了，是出门活动的好机会。