We needed to ensure valid users get the pages they need, but without prompting for a username and password every time they request one — just once per session.

我们需要确保有效的用户得到他们需要的页面，但不必在每次他们请求一个页面时都提示用户名和密码—每个会话只提示一次。

youdao

Joining the keys will never be true in this case, but is required since IBM Cognos BI requires at least one item per query subject to create a valid join.

本例中连接键不会为true，但却是必需的，因为IBM Cognos BI要求每个查询主题至少要有一项，以创建有效连接。

youdao

Users belonging to a valid AIX group can be included in sudoers, making the sudoers file more manageable with fewer entries per user.

属于有效的aix组的用户可以包含在sudoers中，这样针对单一用户的条目更少，sudoers文件更容易管理。

youdao

Thus they would have an equally valid case for imposing countervailing restrictions on American exports based on per-capita emissions.

FORBES: Uncommon Sense