CHICAGO (AP) _ Grain futures were mixed in early trading Friday on the Chicago Board of Trade. Dec. corn fell by 0.25 cent at $5.00 a bushel. Dec. wheat rose by 0.5 cent at $6.84 a bushel. Dec. oats was up 1.75 cents at $4.36 a bushel. Nov. soybeans fell by 1.25 cents at $12.86...