节日里人们穿戴一新，喜气洋洋。A. During the weekends, people are dressed in new clothes, looking very happy.B. During the festival, people are dressed in new clothes, looking very happy.C. During the festival, people are dressed in old clothes, looking very happy.D. During the festival, people are dressed in new clothes, looking very unhappy.

本题考查对中文句子的英文翻译理解，解题思路是将中文句子拆分成关键部分，然后逐一分析每个英文选项与中文关键部分是否匹配。

• 中文句子“节日里人们穿戴一新，喜气洋洋”包含三个关键信息：“节日里”“穿戴一新”“喜气洋洋”。
• 分析选项A：“During the weekends”表示“在周末”，与中文句子中的“节日里”不匹配，所以选项A错误。
• 分析选项B：“During the festival”对应“节日里”，“are dressed in new clothes”对应“穿戴一新”，“looking very happy”对应“喜气洋洋”，该选项与中文句子的关键信息完全匹配，所以选项B正确。
• 分析选项C：“are dressed in old clothes”表示“穿着旧衣服”，与中文句子中的“穿戴一新”不匹配，所以选项C错误。
• 分析选项D：“looking very unhappy”表示“看起来很不开心”，与中文句子中的“喜气洋洋”不匹配，所以选项D错误。