The plural form of "clase" is "clases."
Unas clases
There is no plural form. Do and Do not are verbs
The plural form of him, her, or it is them. (objective pronouns)
The plural form of "is" is "are."
The plural form of "I" is "we."
Unas clases
If it is the present you want, that would be the first-person plural, which in this case is "somos".
Estás/estais en la clase setecientos veintiocho. (Singular/plural; with accent on 'a')
¿Termina a las dos la clase?
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.
"Groceries" is the plural form of "grocery."