The plural form of "clase" is "clases."
Unas clases
The plural form of "do" is "do" and the plural form of "don't" is "don't." These words do not change in the plural form when used in a sentence.
The plural form of him, her, or it is them. (objective pronouns)
The plural form of "I" is "we."
The plural form of "was" is "were."
Unas clases
If it is the present you want, that would be the first-person plural, which in this case is "somos".
¿Termina a las dos la clase?
Estás/estais en la clase setecientos veintiocho. (Singular/plural; with accent on 'a')
The plural form of "do" is "do" and the plural form of "don't" is "don't." These words do not change in the plural form when used in a sentence.
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."
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
"Groceries" is the plural form of "grocery."
The plural form of "meter" is "meters."
The plural form of the demonstrative pronoun 'that' is those.