please tell how can screwdriver be wheel and axle

A screw driver acts as a wheel and axle. Wheel and axle is a form of simple machine and constitute of two cylinders with different radius. The cylinder with larger radius is termed as wheel and the one is smaller radius is axle. The are joint in such a way that if axle is rotated it results in the rotation of wheel also.

Screw driver acts as wheel and axle because when screw driver is kept on the slot of screw and is rotated it results in rotation of screw.  The screw driver act as axle and screw as wheel.