Question

he is reading a book.（变否定句)

Answer 1

He is not reading a book.

Answer 2

he is reading a book.（变否定句)
He is not reading a book

Answer 3

否定句是:He is not reading a book.
意思是：他不是在看书。
is not可以缩写为isn't。
He isn't reading a book.

Answer 4

He is not reading a book.

Answer 5

He isn't reading a book.
现在进行时代的否定句，直接在助动词be的后加not。