许多信纸和一个信封用英语怎么说

Many sheets of writing paper and an envelope can be referred to as "stationery".
The word "stationery" comes from the word "stationery supplies", which refers to the paper products used for writing and printing, including paper, envelopes, and writing implements.
Example sentence in English:
"I need to buy some new stationery for work."
"She wrote a letter on the pretty stationery that she got from Paris."
中文翻译:
"我需要买些新的文具用品。"
"她在那张她从巴黎带回来的漂亮信纸上写了一封信。"