一年一度最盛大英文

"一年一度"的英文表達是 "yearly" 或者 "annually"。這兩個詞都可以用來形容某個事件是每年發生一次的。例如：

• The company hosts a yearly/annual conference for its employees.
• We have a family reunion annually/yearly to catch up with each other.

"最盛大" 的英文翻譯可以是 "the grandest" 或者 "the most spectacular"，這取決於你想要強調的是規模還是視覺效果。例如：

• The grandest/most spectacular fireworks display of the year is on New Year's Eve.
• The yearly/annual music festival is known for being the grandest/most spectacular event of its kind.

所以，如果你想要表達「一年一度最盛大的活動」，可以說：

• The grandest/most spectacular event of the year is the yearly/annual festival.

請根據上下文選擇最合適的辭彙。