23．Paragraphs 1&2______________.
24．Paragraph 3______________.
25．Paragraph 4______________.
26．Paragraph 5______________.
27．One advantage of CD—RWs is that they can____________like floppy disks．
28．The author predicts it will not before a new technology is invented for music recording．
29．The laser beam—emitting device and the receiver are considered to___________0f a CD player．
30．Space probes could not____________ without using digital codes．
