【Answer】21; 6
【Explanation】Consider the maximum. 2 circles can divide into at most 4 parts. Adding one line increases 4 parts; adding a second line increases another 6 parts; adding a third line increases another 7 parts, so the maximum is $4+4+6+7=21$ parts; the minimum is when there are no intersections, originally 1 plane, plus 5 shapes, $1+5=6$ parts
5、On the plane, there are 2 circles and 3 straight lines, what is the maximum number of parts the plane can be divided into? $\qquad$

What is the minimum number of parts the plane can be divided into? $\qquad$