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Câu hỏi :

Some people return to college as mature students and take full- or part-time training courses in a skill will help them to get a job. The development of open learning, (1)______ it possible to study when it is convenient for the students, has increased the opportunities available (2)_______ many people. This type of study was formerly restricted to book-based learning and (3)________ course but now includes courses on TV, CD-ROM or the Internet, and self-access courses at language or computer centers.