he likes coffee,but i don‘t 【like coffee】
（ 这里主语为 I,对动词like 表示否定,借助于don't）
she likes tea,but he doesn't【like tea】
（这里主语为he,对动词like 表示否定,借助于doesn't)
he is eating some bread,but she isn't【eating any bread】
( be动词is,否定直接加not,为isn't ）
she can type very well,but he can't【type very well】
（can 否定形式,直接加not,为can't）
they are working hard,but we aren't【 working hard】
（be 动词are,否定直接加not,为aren't)
he is reading a magazine,but i am not 【 reading a magazime】
( be动词am,否定直接加not,为 am not )