1. Today is the birthday of the party!
2. The Communist Party of China was founded on July 1, 1921 in Shanghai, China.
3. July 1st is the birthday of our party.
4. We celebrate the birthday of the Chinese Communist Party every year.
5. Party's day is a day of remembrance and celebration for the founding of the Communist Party of China.
希望这些句子能够帮助你更好地表达关于党的生日的英语内容。