he is a success in writing novels.这里为什么用a,求【详解】

He is i__(单词) in writing novels. He is really______great success on business 问为 么这里为什么要用a来修饰s He is writing a letter He is writing a letter in his study. （否定） He is _______ in writing a love novel Nam Dan is a w---------- and he usually w------- novels. He is writing a letter with a pen.和He wrote the letter in pe who is in the room? Mr.Smith.He ____ a story.A is writing B As a teacher,he is （ ）success 用英语解释he is busy writing a job application He is writing a letter____the corner. He is writing a letter now,he()free in an hour.