Directions: Complete the following Passage by using ONE word that best fits the context.

     New studies show how food and its production affect the globe and its climate. The process of making

a hamburger, for example, requires lots of energy. A cow has to be fed and raised on farmland. And cow

waste is a major source of methane (沼气) 1______ especially powerful greenhouse gas. The cow has to

be killed. The meat has to be processed and shipped, 2______ takes fuel. Most of the cow won't even be

used for meat people eat. By the time a hamburger finally lands on a dinner plate, 3______ has made bad

effect on the environment.

     We can reduce the production of global warming gases by eating less beef. Other kinds of meat like pork

and chicken do 4______ harm to the environment at least 5______ terms of the amount of greenhouse gases

released. 6______, all kinds of meat are harder on the planet than vegetables. 7______ changing our diet to

less meat and more vegetables, as it turns 8______, may do the world some good.