用方框中所给单词的适当形式填空，使短文通顺、正确、连贯(每个单词限用一次)。 something,   not,   tree,   simply,   spend,   you,   why, that,   they,   if,   little,   go,   in,   on,   protect The Earth needs a helping hand The Earth is getting warmer because of the activities of people. We cut down and burn 1______ and send gases into the air with our cars and factories. Can we do anything about it? Sure. We may 2______ be leaders or scientists but we can play our part in 3______ the planet. Here are two ideas. Bike, don't ride to school Do you 4______ to school by bus or by bike? If you bike, you are doing 5______ for the Earth. Buses, cars, trains and planes produce a lot of carbon dioxide (二氧化碳). If you live near to your school, 6______ not bike there on warm spring mornings? Or, you can 7______ walk to school to save energy. Wash the green way Do you help your mom and dad wash clothes? Then wash them 8______ an energy-saving way. A recent study by Cambridge University found 9______ 60 percent of the energy used on a piece of clothing is 10______ in washing and drying it. Over ita lifetime, a T-ahirt can send up to 4 kilograms of carbon dioxide into the air. 11______ you wash your own clothes, wash them in cold or warm water to save energy, but not hot water. Wash your clothes when 12______ fill up the machine. Use the most energy-saving machine you can find. Some new ones use as 13______ as one-fourth of the energy of older machines. When they're clean, dry 14______ clothes the natural way, by hanging them 15______ a line rather than putting them in a dryer. In all, you can cut the carbon dioxide used in washing by 90 percent.