1. Please send the email to john@example.com, with the subject line "Meeting at 3 pm" and cc me at mary@example.com.
请将邮件发送至john@example.com，主题为“下午3点开会”，并抄送给我mary@example.com。

2. The arroba symbol is commonly used to denote the "at" symbol in Spanish.
在西班牙语中，arroba符号常用来代表“at”符号。