Letters as mails that you receive: 信 (xin)
Alexis John OR Alex is John
迈克
It's "开"。
Beijing is spelled as εδΊ¬ in Chinese characters.
唐娜 (Tángnà)
Chinese doesn't have letters, each word is a specific character. It would most likely be the exact same as English.
亚历克西斯 Yà lì kè xī sī
Alexis
Alicia
Unlike Western languages like French, German, and English, Chinese does not have an alphabet. Written Chinese doesn't have letters that spell out words. Instead, it has characters that represent the different words of the language. The character for "open" is 開. In Simplified Chinese this is written 开.
Chinese does not use letters... this question can not be answered. Chinese instead uses character-words and thus only old, traditional words can be used.