A．The author comments on three different opinions.
B．The author favors one of the three opinions.
C．The author explains an opinion of his won.
D．The author revises someone else"s opinions.

A．She is going to miss her first class.
B．She prefers going to the dentist later in the day.
C．The man will be finished before his first class.
D．The man might sleep late and miss his appointment.

A．It was a serum prepared from the blood of patients who had been stung.
B．It was a serum prepared from poison extracted from bees.
C．It was a serum prepared from crushed bodies of bees.
D．It was a serum prepared from a placebo and a crushed-body extract.