President () was the first American president ordering school desegregation in the South.
A. John F. Kennedy
B. Jimmy Carter
C. Franklin Roosevelt
D. Richard Nixon
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The United States ranks () in the world in the total value of its economic production.
A. first
B. second
C. third
D. fourth
试述OEM生产模式是如何使OEM厂商和EMS厂商实现双赢的。