Wheat:  Net sales of 476,000 metric tons for 2018/2019 were up 40 percent from the previous week, but unchanged from the prior 4-week average.      Corn:    Net sales of 382,500 MT for 2018/2019--a marketing-year low--were down 62 percent from the previous week and 72 percent from the prior 4-week average.    Soybeans:    Net sales of 293,600 MT for 2018/2019 were reported for Spain (188,000 MT, including 195,000 MT switched from unknown destinations and decreases of 13,000 MT), the Netherlands (113,600 MT, including 86,000 MT switched from unknown destinations), Mexico (111,500 MT, including decreases of 1,100 MT), Thailand (77,700 MT, including 66,000 MT switched from unknown d...