1. no city has cables directly. a. lay b. are laying c. laid 2. computers to perform series of mathematical operations. a. are used b. are using c. have used 3. power losses, thick wires should be used. a. reducing b. to reduce c. having reduced 4. for information it must be attached to a radio – frequency carrier wave. a. to be transmitted b. will be transmitted c. transmitted 5. various installations _have been to transform electric power into mechanical and heat power. a. have been used b. are using c. are being used 6. the experiment to be continued . a. reports b. is reporting c. is reported 7. a computer to possess four main parts. a. has been known b. is known c. knows 8. the atmosphere to extend several hundred kilometers above the earth. a. proves b. has been proved c. is proved 9. transistor batteries to be used in systems that have to operate on weak signals, for example, in ultra-long-distance space communications. a. expected b. have been expected c. were expected 10. materials very high resistance are called insulators. a. having b. have c. are having

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