单项选择题

When Columbus reached the New World, com was the most widely grown plant in the Americas. This plant’s range extended from what is now southern Canada to lower South America. At that time some tribes cultivated it at sea level, others at elevation(海拔高度) of more than 11 000 feet.
"Columbus had no way of knowing that corn was far more valuable than the spices(香料) and gold he had hoped to find." said Frances B. King, a professor at a university of Pittsburgh. Through human intervention, this plant has developed into several hundred races, or varieties. Their heights vary from 2 to 12 feet, and their maturity ranges from little more than 2 months to almost a year. Their ears vary not only in color, but also in size.
Unlike other cereals(谷类), corn bears little resemblance to its wild ancestors. In fact, it differs from the appearance of its immediate ancestors more than any other cultivated plant known. From humble origins as a lowland grass, corn developed into the western world’s important grain. As its high yields allowed communities to grow far beyond what early agriculture could feed, most scientists viewed corn as having largely fueled pre-Columbian growth and civilization.
Now, new findings are greatly altering researchers’ notions about the time when com revolution occurred. New dates for its emergence from Mesoamenrica do not support the widely held view. The evidence now suggests that the signs of corn in Americas can date back 5 500 years at least.
The widely held view was challenged by （）.

A．a new revolution
B．new findings about corn
C．the signs of com 5 500 years ago
D．new dates for communities’ emergence

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If you find yourself stressed by the economic forecast, threat of job loss, or have been laid off, the situation is manageable. John Wakeman, program director of the Stress Treatment Center at Ochsner Clinic, New Orleans, La. , who has given numerous stress management training sessions for major industries and businesses, says that, when confronted with altered circumstances, it is our nature to either revert back to the status quo(现状) or to adapt and to do so quickly so that it’s no longer a change. My suggestion is to adapt quickly. If laid off, avoid a doom-and-gloom attitude, which adds to the stress. (2) Accept that changes are inevitable in a lifetime and occurrences such as job loss frequently bring opportunities that would not be available if you were not facing the crisis. Some people find an even better occupational situation. (3) Instead of responding to layoff as a personal insult, view it as a sign of the economic times and the fact that the business could not keep its employees. Maintain a routine and keep your social contacts. Don’t sit at home. Remain active. Use energy constructively. Don’t vent (发泄) irritability and frustration from stress on your family, but channel it into exercise or work on a project. Polish your resume, network with others in your field, and write letters to prospective employers. Keep informed about the job market by reading employment journals, trade publications, and newspapers. Competition is keen, so expect your search to take time. (4) When a person is turned down repeatedly, it does try [his or her] self-esteem, but you have to remember what you accomplished before you were laid off. No one can erase those achievements from your history. You have somethings to offer. Many people feel threatened by change and become inflexible, Wakeman points out. You may find that you need to be more open about relocating to a place where employment is available. (5) Keep an open mind and be flexible about the possibility of a change requiring relocation or taking on new assignments.

单项选择题

On the whole, the attitude Steven Case holds for the Internet’s future development is （）.

A．pessimistic
B．optimistic
C．doubtful
D．unknown