是a user还是 an user?为什么?

是a user还是 an user?为什么? user User user=Session[user] as User其中 User和user各代表什么意思?我是这样理解的,不知是否正确：我认为User是一个类,而user是一个对象,as的用法是把user转换为User类 英语翻译Pre-requisites:• User is logged into a system.• User has relevant permissions (for example sa/sa user).• An Agreement with ‘Active/Executed’ status/stage is created.Main Case.1.User opens an ‘Active/Executed’ Agr a user study?标准翻译 already a ubi.com user? an owner's [user's] manual是什么 user中文翻译 user是什么意思 user profile user是什么 user access end user ${USER.u_name } User name user address user-contributed user not