請依下文回答第 42 題至第 46 題：
       When I was 17, I read a quote that went something like: "If you live each day as if it was your last, someday you'll most certainly be right." It made an impression on me, and since then, for the past 33 years, I have looked in the mirror every morning and asked myself: "If today were the last day of my life, would I want to do what I am about to do today?" And whenever the answer has been "No" for too many days in a row, I know I need to change something.
       Remembering "I'll be dead soon" is enough to help me make the big choices in life. Because almost everything--all external expectations, all pride, all fear of embarrassment or failure--these things just fall away in the face of death, leaving only what is truly important. Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart.

請依下文回答第 47 題至第 50 題：
       Most progress against air-pollution has been cheaper than expected. Smog controls on automobiles, for example, were __47__ to cost thousands of dollars for each vehicle. Today's new cars emit less than 2 percent as much smog-forming pollution as the cars of 1970, and the cars are still as affordable today as they were then. Acidrain control has cost about 10 percent of what was expected in 1990, when Congress __48__ new rules. At that time, opponents said the regulations would cause a "clean-air recession"；__49__ , the economy boomed. Greenhouse gases, being global, are the biggest air-pollution problem the world ever__ 50__ .