This is a letter, or more correctly, an invitation letter. 这是一封信，说得更正确些，是一封邀请信。
A combination of two or more elements or parts. 复合物由两种或多种元素或部分构成的混合物
Pupils with 90% or more are awarded Grade A. 满90分的学生评为甲等。
A computer operation, similar to switching, where a selection is made between two or more possible courses of action depending upon some related fact or condition. 一种类似于开关的计算机操作。根据有关的事实或条件，对两个或更多可能的操作路径进行选择。
Data that describes the significant characteristics of a user, a group of users, or one or more computer resources. 描述一个用户、一组用户或一至多个计算机资源重要特征的数据。
