你能把这封邮件转发给经理吗？

Can you ___forward this email to the manager?

我需要配置fw来保护家庭网络免受黑客入侵。

I need to set up the ___fw to protect my home network from hackers.

这个湖泊是淡水生态系统的重要部分。

This lake is an important part of the ___freshwater ecosystem.