| More than a year has passed since the
space shuttle Columbia broke into pieces over central Texas. This past January
President Bush announced a long-term program of space exploration that would
return human beings to the Moon, and thereafter send them to Mars and beyond. As
this magazine (Natural History) goes to press, the twin Mars Exploration Rovers,
Spirit and Opportunity, are wowing the scientists and engineers at the rovers’
birthplace--NASA’s Jet Propulsion Laboratory (JPL)--with their skills as robotic
field geologists. JPL’s official rover Web site is being stampeded by visitors.
The confluence of these and other events resurrects a perennial debate: with two
shuttle failures out of 112 missions, and the astronomical expense of the manned
space program, can sending people into space be justified, or should robots do
the jo A. hacked severely B. clicked frequently C. closed forever D. neglected purposely [填空题]Every country has its own historic backgrounD．
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Dining Custom
Every land has its own dining custom, and the United States is no exception. Americans feel that the first rule of being a polite guest is to be on time. If a person is invited to dinner at 6:30, the hostess expects him to be there at 6:30 or not more than a few minutes after. Because she usually does her own cooking, she times the meal so that the coffee and meat will be at their best at the time she asks the guest to come. If he is late, the food will not be so good, and the hostess will be disappointed. When the guest can not come on time, he calls his host or hostess on the telephone, gives the reason, and tells at what time he thinks he can come 我来回答: 提交
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