the boy pretended to be reading a book when the teacher came in.改为强调状语的强调句
问题描述：
the boy pretended to be reading a book when the teacher came in.改为强调状语的强调句
答
it was when the teacher came in that the boy pretended to be reading a book .
改为强调句后,去掉it is .that后句子还是通的,知道这一点就容易改了