"Happy Mid-Autumn Festival" is a greeting you can use to wish someone a happy holiday in English during the Mid-Autumn Festival. "Mid-Autumn Festival" is the English name for the Chinese holiday that is also known as the "Moon Festival" or "Zhongqiu Festival." The Mid-Autumn Festival is a traditional holiday that is celebrated in many East Asian countries, and it is typically held on the 15th day of the eighth month in the Chinese lunar calendar. It is a time for families and friends to come together to enjoy the full moon, eat mooncakes, and participate in other festive activities. If you want to say "good morning" in English during the Mid-Autumn Festival, you could say "Happy Mid-Autumn Festival and good morning!"