"Writing a letter on the beach" is a common phrase used to describe the act of writing a letter while on a beach. The phrase is often used to convey a sense of relaxation and tranquipty, as being on a beach is often associated with vacation and leisure.

Here are a few examples of the phrase being used in sentences:

"I spent the afternoon writing a letter on the beach, watching the waves roll in."
"It was such a beautiful day that I couldn't resist the urge to pull out my pen and paper and write a letter on the beach."
"I always find that my thoughts flow more freely when I'm writing a letter on the beach. The sound of the waves and the warmth of the sun seem to help me clear my mind and focus."

中文翻译:

"我整个下午花在沙滩上写信，看着海浪滚滚而来。"
"天气太好了，我忍不住拿出笔和纸在沙滩上写信。"
"我发现，当我在沙滩上写信时，我的思绪会更加顺畅。海浪的声音和阳光的温暖似乎有助于我清除思绪，专注。"