plateau
Plateaus, or less commonly, plateaux
Bridges is the plural form of bridge.
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
There is no plural form for the word, countries. This word itself is a plural.
There is no plural form of pupae. Pupae is the plural form of pupa.
plateaus or plateaux
Plateaux is already plural. Plateau is the singular form
"Plateau" refers to a raised flat area of land, while "plateaux" is the plural form of plateau, referring to multiple flat areas of land. "Plateau" is used for a single flat-topped landform, whereas "plateaux" is used to describe multiple such landforms.
Plateaus, or less commonly, plateaux
Plateaus is acceptable. The word is of French origin, so the strict plural ought to be plateaux.
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 "was" is "were."
The plural form of "I" is "we."
The plural form of "is" is "are."
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.