2 . Space exploration has always been the province of ________: The human imagination readily soars where human ingenuity (聪明才智)struggles to follow. A Voyage to the Moon, often cited as the first science fiction story, was written by Cyrano de Bergerac in 1649. Cyrano was dead and buried for a good three centuries ________the first manned rockets started to fly.  

In 1961, when President Kennedy declared that America would send a man to the moon by the________’s end, those words, too, had a dreamlike quality. They resonated with optimism and ambition in much the same way as the most famous ________ speech of all, delivered by Martin Luther King Jr. two years later. By the end of the decade, both visions had yielded concrete results and________American society. And yet in many ways the two dreams ended up ________each other. The fight for racial and economic equality is intensely pragmatic (讲求实用的)and immediate in its impact. The urge to explore space is just the opposite. It is figuratively and literally otherworldly in its ________.  

When the dust settled, the space dreamers lost out. There was no grand follow-up to the Apollo missions. The technologically compromised space shuttle program has just come to an end, with no________. The perpetual argument is that ________ are tight, that we have more pressing problems here on Earth. Amid the current concerns about the federal deficit, reaching toward the stars seems a dispensable luxury—________ saving one-thousandth of a single year’s budget would solve our problems.  

But human ingenuity struggles on. NASA is developing a series of robotic probes that will get the most bang from a buck. They will serve as modern Magellans, ________out the solar system for whatever explorers follow, whether man or machine. On the flip side, companies like Virgin Galactic are plotting a bottom-up assault on the space dream by making it a reality to the public. Private spaceflight could lie within ________ of rich civilians in a few years. Another decade or two and it could go mainstream.  

The space dreamers end up benefiting all of us—not just because of the way they expand human knowledge, or because of the spin-off ________ they produce, but because the two types of dreams feed off each other. Both Martin Luther King and John Kennedy appealed to the idea that humans can ________what were once considered inherent limitations. Today we face seeming challenges in energy, the environment, health care. Tomorrow we will transcend these as well, and the dreamers will deserve a lot of the credit. The more evidence we collect that our species is ________greatness, the more we will actually achieve it.