名词
中文翻译：信封
同义词：
['letter', 'envelope', 'packet例句：1. She carefully placed the letter in the mailbox.（她小心翼翼地把信放进邮箱。）']
例句：
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1. She carefully placed the letter in the mailbox.
她小心翼翼地把信放进邮箱。
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2.The postman delivered the package to her doorstep.
邮递员把包裹送到了她的门前。
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3. He sent a postcard from his travels around the world.
他从世界各地的旅行中寄了一张明信片。