我登录了工作电脑，但系统宕机了。

I ___logged ___on to my work computer, but the system was down.

要访问课程材料，你必须登录大学门户网站。

To access the course materials, you must ___log ___in to the university portal.

员工在使用公司网络前必须登录。

Employees are required to ___log ___on before they can use the company network.