This led to the development of a special magnetic plastic tape. Whereas the paper tape carried the programmed instructions   1    a series of holes punched in the tape, the plastic tape carried the instructions as a series of magnetic dots . The plastic tape was much   2   than the paper tape, which solved the problem of frequent tearing and breakage.    3    , it still left two other problems.
The   4    of these was that it was difficult or impossible to change the instructions entered on the tape. To make even the most minor adjustments in a program of instructions, it was necessary to interrupt machining operations and make a new tape. It was also still necessary to run the tape through the reader, as many times as there were parts to be produced. Fortunately, computer technology   5  a reality and soon solved the problems of NC associated with punched paper and plastic tape.
The    6   of a concept known as direct numerical control (DNC) solved the paper and plastic tape problems associated with numerical control by simply eliminating tape as the medium for carrying the programmed instructions . In direct numerical control, machine tools are tied, via a data transmission link, to a host computer. Programs for operating the machine tools are stored in the host computer and fed to the machine tool as needed via the data transmission linkage. Direct numerical control    7    a major step forward over punched tape and plastic tape.     8    , it is subject 9        the same limitations    10     all technologies that depend on a host computer . When the host computer goes down, the machine tools also experience downtime. This problem led to the development of computer numerical control.

1.   A. as          B. on            C. at          D. with             
2.   A. strong       B. strongest      C. stronger      D. strength          
3.   A. But         B. However       C. So          D. Since
4.   A. important     B. more important  C. importance    D. most important
5.   A. becoming     B.  became       C. become      D. becomes
6.   A. development  B. develop       C. developed   D. developing
7.   A. represent    B. representing     C. represents   D. represented
8.   A. Since       B. However       C. But         D. So
9.   A. to          B. as             C. on         D. in
10.  A. to          B. with           C. as          D. on

Key
1. A      2. C      3.B       4.D       5. B   
6. A      7. D      8. B      9. A      10. C