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

I'm sorry to complain so much. It's just not a good day.
我很抱歉发了这么多牢骚。今天可不是个好日子。
Tell me about a good day.
和我说说那些美好的日子。
A good day and the size and magnitude of the event leaves a lasting impression.
一个好的一天的规模和活动的规模留下了难以磨灭的印象。
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's a good day for playing practical jokes on your friends.
这是一个对你的朋友们开实际玩笑的好日子。
We did a good day's work yesterday.
昨天我们整整工作了一天。
I mean, this is a very good day.
我是说，今天是个好日子。
Good morning! Today will be a good day.
早上好！今天会是个好日子。
It is a good day to catch up on back reading and other assignments.
周日用来补上拖欠的阅读任务和其他作业的好时机。
It's a good day for an important meeting because things are sure to go your way.
这也是个举行重要会议的好日子，因为事情开始顺应你的期待而动了。