A．to test whether smoking has a positive effect on the mental capacity of smokers
B．to show how smoking damages people’’s mental capacity
C．to prove that smoking affects people’’s regular performance
D．to find out whether smoking helps people’’s short-term memory

A．The furnished apartment was inexpensive.
B．The apartment was provided with some old furniture.
C．The furniture in the market was on sale every Sunday.
D．The furniture he bought was very cheap.