[判断题]电伤是指触电时电流的热效应、化学效应以及电刺击引起的生物效应对人体外表造成的伤害。( )
A.正确
B.错误

Shortages of flu vaccine are nothing new in America, but this year’s is a whopper. Until last week, it appeared that 100 million Americans would have access to flu shots this fall. Then British authorities, concerned about quality-control problems at a production plant in Liverpool, barred all further shipments by the Chiron Corp. Overnight, the U.S. vaccine supply dwindled by nearly half and federal health officials found themselves making an unusual plea. Instead of beseeching us all to get vaccinated, they’re now urging most healthy people between the ages of 2 and 64 not to. "This reemphasizes the fragility of our vaccine supply, " says Dr. Martin Myers of the National Network for Immunization Information, "and the lack of redundancy in our system. "
Why is such a basic health service so easily knocked out Mainly because private companies have had little incentive to pursue it. To create a single dose of flu vaccine, a manufacturer has
A. complicated process, high cost, low profit and high risk
B. shortages of fertilized chicken eggs
C. difficulty in growing live virus
D. fast changing of flu virus