Beliefs
Believe is a verb, not a noun, and therefore has no plural. The noun form of the word is belief, and the plural of belief is beliefs.
Octopi, I believe...
I believe that it is Christmases.
Octopi, I believe...
The word 'believes' is a verb (believe, believes, believing, believed). The noun form is belief, the plural noun is beliefs.
Yes, the noun 'make believe' is a singular uncountablenoun, it has no plural form.
Yes - "opportunity" is singular; "opportunities" is plural. From Latin "opportunitas" 3rd declension, I believe.
Yes, it is a noun. It is a plural noun referring to the stars or the night sky.
The subject of the sentence "there" is a plural pronoun, identified as plural by the verb for a plural subject "are"The direct object noun "moose" is a plural noun, identified as plural by the adjective "more", indicating a quantity.The subject of the adverbial clause is "people", a plural noun.
The plural noun is halves.
The plural noun for path is paths. The plural noun for patch is patches.
The plural noun of general is generals. Generals is a regular plural noun.