Question generation is a reading comprehension strategy whereby readers ask and answer meaningful questions about the important points or main ideas of a text. Using this strategy, students ask and answer their own questions rather than only answering questions provided by the book or the teacher.
According to the above paragraph .......

readers should ask and answer the questions in their books in order to comprehend the texts

students who produce questions on their own can hardly be successful in finding the main ideas of the reading comprehension

Asking and answering questions produced by readers can help them figure out the main idea of a reading   

reader can easily understand the readings by producing their own questions without answering any of them