John has a pen pal.
:John doesn't have a pen pal.
My pen pal doesn't live in shanghai.
就是用助动词do ,词形变化,三单等都体现在助动词do上面,动词不变.
知识在于点滴积累,更在于不懈努力.
——另外,正在冲采纳率,请记得采用,