若一个圆锥的底面半径为3cm,母线长为5cm,则这个圆锥的全面积为（    ）

A．15π cm²

B．24π cm²

C．39π cm²

D．48π cm²

After supper, Mary often ________ along the river. [ ]

A. take a walk

B. taking a walk

C. takes a walk