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)。

The Earth needs a helping hand

　 The Earth is getting warmer because of the activities of people. We cut down and burn　 56　 　and send gases into the air with our cars and factories. Can we do anything about it? Sure. We may　 57　 be leaders or scientists but we can play our part in 　58　 　the planet. Here are two ideas.

Bike, don't ride to school

　 Do you 　59　 　to school by bus or by bike? If you bike, you are doing 　60　 　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, 　61 　not bike there on warm spring mornings? Or, you can　 　62　 　walk to school to save energy.

Wash the green way

　 Do you help your mom and dad wash clothes? Then wash them 　63　 　an energy-saving way. A recent study by Cambridge University found 　　64　 　60 percent of the energy used on a piece of clothing is 　　65　 　in washing and drying it. Over it a lifetime, a T-shirt can send up to 4 kilograms of carbon dioxide into the air.

　 　66　　 you wash your own clothes, wash them in cold or warm water to save energy, but not hot water. Wash your clothes when 　67　 　fill up the machine. Use the most energy-saving machine you can find. Some new ones use as 　　68　 　as one-fourth of the energy of older machines. When they're clean, dry 　　69　 　clothes the natural way, by hanging them 　70 　a line rather than putting them in a dryer. In all, you can cut the carbon dioxide used in washing by 90 percent.