One of the most fundamental concepts in the area of 1 manufacturing technologies is numerical control (NC). Prior 2 the advent of NC, all machine tools were manually operated and controlled. 3 the many limitations associated 4 manual control machine tools, perhaps none is more prominent than the limitation of operator skills. With manual control, the quality of the product is 5 related to and limited to the skills of the operator. Numerical control represents the first major step away 6 human control of machine tools.
Numerical control means the control of machine tools and other 7 systems through the use of prerecorded, 8 symbolic instructions. Rather than operating a machine tool, an NC technician writes a program that issues operational instructions to the machine tool. For a machine tool to be 9 controlled, it must be interfaced with a device for accepting and decoding the programmed instructions, known as a reader.
Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines, they can produce parts more uniformly, they are faster, and the long-run tooling costs are lower. The 10 of NC led to the development of several other innovations in manufacturing technology.
1. A. advance B. advancing C. advanced D. advancement
2. A. to B. at C. of D. as
3. A. From B. Among C. Between D. All
4. A. as B. from C. with D. to
5. A. directly B. direct C. direction D. to direct
6. A. since B. from C. for D. to
7. A. manufacture B. manufactured C. manufacturing D. manufacturer
8. A. write B. writing C. wrote D. written
9. A. number B. numerically C. numeric D. numerical
10. A. development B. developed C. developing D. develop
Key
1. C 2. A 3. B 4. C 5. A
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