Chicago grains futures either drop or remain steady on Thursday, supported by stronger-than-expected export sale, but weighed by the setback in wheat prices. Wheat suffered some extra pressure on speculation that rain will revive U.S. crops that were threatened by dry weather recently. The most active corn contract for December delivery remained unchanged, to close at 6.055 U.S. dollars per bushel. December wheat dropped 9.25 cents, or 1.5 percent, to 6.16 dollars per bushel. November soybean was unchanged at 11.6375 dollars per bushel. According to a report released by U.S. Department of Agriculture, weekly export sales for corn totaled 1.291 million tons, which was near 450,000 above expectations. Weekly export sales for wheat came in at 431,200 tons, which was right on trade expectations and close to last week\'s total. Weekly export sales for soybeans totaled 741,800 which was near the high end of trade expectations. Despite the fact that crude oil, metal and stock markets rallied on Thursday, many agricultural markets were choppy to lower for much of the session. Wheat suffered some extra pressure, as rains expected in U.S. southern Plains may breathe life into a struggling early crop, limiting upside.