V. Use the correct form of the verb in brackets 1. I hope a time machine __________________ one day. ( invent) 2. Nothing _________________until they reach the decision. ( do) 3. Sondong Cave ___________________by thousands of people sofar. ( visit) 4. Don’t worry. If you don’t understand , the teacher_________________to you . ( explain) 5. your parents _____________to go to work very early ? ( used) VI. Read the pasage the choose the best answer. In the modern world, people depend on energy to power their everyday lives. A wide range of power-run devices and modern conveniences (1)..........., and although it may seem that we will not be in danger of living without those conveniences, the fact is that many supplies of energy are running out rapidly. Scientists are constantly (2)........ new sources of energy to keep modern society running. Whether future populations will continue to enjoy the benefits of abundant energy will depend (3)............ the success of this search. Coal, oil and natural gas are now being used widely. (4).........., these supplies are limited, and they are a major source of pollution. Therefore, the existing alternative energy sources must be improved or futher explored and developed. These include nuclear, water, solar, and wind power, as well as energy from new, (5)................... types of fuels. Each of these, however, has advantages and disadvantages. 1. A. are used B. used to C. are using D. use 2. A. looking into B. searching for C. researching D. finding 3. A. on B. for C. with D. in 4. A. Moreover B. Because C. Although D. However 5. A. polluting B. polluted C. non polluting D. pollution