Mike is writing a letter（改为否定句）怎么改

Mike is writing a letter（改为否定句）怎么改 Mike is writing a letter to his father (改为同义句） mike is writing a letter to his father.改为同义句 she is writing a letter to her pen pal[改为否定句} He is writing a poetcard .(改为否定句） this is letter A.改为否定句 I'm writing a letter athome.(改为否定句,一般疑问句,肯定回答、否定回答,提问） He is writing a letter in his study. （否定） maybe he is a teacher改为否定句怎么改? I fished writing a letter .(改为一般疑问句和否定句) Tom is writing to his friend.（该怎么改啊?否定句 ） This is my teacher.(改为否定句）怎么改?