The slogan can be a period.

Solution: period: s = 3.14× (2r) 2-3.14r2 = 9.42r2;

Comma: s =

1

2

×3. 14×（2r）2 = 6.28 R2；

Question mark: s =

three

four

×【3. 14×（2r）2？ 3. 14r 2】+3. 14r 2 = 10.205 R2；

Because10.205r2 "9.42r2" 6.28r2,

So the question mark paint is used in large quantities.