Miss Guo ______ (teach) us Chinese this term.She ______ (be)

Miss Guo ______ (teach) us Chinese this term.She ______ (be) a very good teacher.She often ______ (talk) with us after class.Many of us like ______ (talk) with her.Now,she ______ (talk) with Lily
teaches,is,talks,talking,is talking
请问为什么第四个用talking 而不用talk