Sometimes it is necessary to (1) ________our habits. Saving energy is one illustration. If we can (2) ________more energy, such as water and electricity, we can help keep the natural enviroment safe. Saving water, for example, helps preserve our rivers and reservoirs. If we usually take 10- minute showers, in this case should try to take shorter showers. When we go out, we (3)________remember to shut off electronic devices such as televisions and computers. Turning (4) ________ the light is another example of saving electricity. In short, remembering to help the enviroment, such as by saving energy, is one of our most (5) ________responsibilities. 1. A. exchange B.turn C.change D.make 2. A. help B.save C. cut D. saving 3. A. must B. may C. had D. should 4. A. on B. in C. without D. off 5. A. important B. basic C. necessary D. main