The plural form of gnu is also gnu.
The plural of gnu is gnu or gnus, both are acceptable.
GNU is operating system
It is an abbreviation of "GNU's not unix!"
GNU DeBugger
GNU Object model environment.
There is no plural form. Do and Do not are verbs
The plural form of him, her, or it is them. (objective pronouns)
Bridges is the plural form of bridge.
The plural form of "is" is "are."
The plural form of "I" is "we."
The plural form of "was" is "were."
The plural form of mouth is mouths. The plural form of month is months. The Mounth is a range of hills in Scotland and does not have a plural form.