He can't visit his aunt this week. He go to the doctor. [ ]
A. have to
B. has
C. has to
答案:C
牙齿的增龄性变化是牙釉质磨耗,牙骨质变薄,牙髓腔变小。()
以下哪种方式不属于软文速成法()
A.评论法
B.总结法
C.学习法
D.案例法