Co-ordinate conjunctions may connect two or more _nouns_ used as the
subject of a verb. As:
_Death_ and _disaster_ follow in the wake of war.
In this sentence, _death_ is just as much the subject of the verb
_follow_ as is the word _disaster_, but no more so. You can omit either
of these words and the other will make a subject for the sentence. They
are both of equal importance, both of the same rank in the sentence, and
neither depends upon the other. These two words taken together form the
subject of the sentence. This is called the _compound subject_, for it
consists of two simple subjects.
Co-ordinate conjunctions may connect two or more nouns used as the
_object_ of a verb.
He studies history and science.
In this sentence the words _history_ and _science_ are both used as
objects of the verb _studies_.
Co-ordinate conjunctions may connect two or more nouns used as the
object of a _preposition_.
He called for the letters and the papers.
In this sentence _letters_ and _papers_ are both objects of the
preposition _for_, connected by the co-ordinate conjunction _and_.