The only times you could possibly use an apostrophe with a pronoun or a verb is to show a contraction. The one very large dog chased the two smaller dogs away. The child who owned the two dogs was angry at the three children who owned the large dog. Sometimes, two dogs will share a bone. Sophisticated writing has a high percentage of complex and compound-complex sentences.
Sentence types depend on the number and types of clauses.
Words most often function in units, either phrases or clauses. A clause is a unit that contains a subject and a matching complete verb. A phrase is any other type of unit. See your text for a more complete list of common subordinating conjunctions. Birds fly .