Computers have been used in teaching for more than twenty years. But a new book says that only now are they changing education. And it predicts that a lot more is about to happen.

The book is called “Disrupting Class: How Disruptive Innovation Will Change the Way the World Learns.” “Disruptive Innovation” is a theory developed by lead author Clayton Christensen, a professor at the Harvard Business School. He says organizations almost always use new, creative technology only to continue what they already do.

New technology should change organizations, he says, and disrupt them in a good way. They should use the technology to do things differently―for example, to serve more needs. The book says the needed disruptive force in education is computer-based learning.

Michael Horn, another author of “Disrupting Class”, told us about a Boston public that he visited. Every student at Lilla G. Frederick Middle School in Dorchester, Massachusetts, has a laptop computer. One class was learning about storms. Michael Horn says the laptops made it possible to truly individualize（使个人化）the lessons, to divide materials by ability level and learning style. At the end of the class, the students all took part in a discussion led by the teacher.

Computer-based learning offers a way for students to take advanced courses not offered at their school, or to retake classes they failed. It also serves those who cannot physically attend school, and students who receive home schooling.

Computer-based learning includes online courses. Enrollments（招生）in online courses have grown sharply. In 2007, the United States had about one million enrollments, not including college courses. Students could be enrolled in more than one course, through schools or education companies. High school students make up about seventy percent of the enrollment. Still, nationally, only about one percent of all high school courses last year were taught online.

But the authors of “Disrupting Class”predict it will be ten percent in about six years. And their research suggests that the number will be about fifty percent by 2019. And Michael Horn says the future of online learning could be even greater in developing countries.

73. Which of the following is TRUE about the book “Disrupting Class”?

A. It was written by more than one author.

B. It thinks the computer affects students’ studies.

C. It introduces a new scientific technology to readers.

D. It has been a best-seller since it was published.

74. Paragraph 4 is written to show                .

A. how modern the Boston public school is  

B. how clever the American students are

C. how well the American teachers teach

D. what computer-based learning is like

75. From the last two paragraphs, we can infer that the authors of “Disrupting Class”think that              .

A. more and more students are interested in “Disrupting Class”

B. those who take online courses are mainly college students

C. more and more high school courses will be taught online

D. enrollments in online courses haven’t grown recently

76. The passage is mainly about              .

A. a new book

B. a new learning way

C. some American writers

D. the advantages of computers