When the futures price of soybean falls, the spot price of soybean will fall (the futures price is the expectation of the spot price and always moves in the same direction), then the price of soybean oil will fall (the price of raw soybean will fall), and then the price of vegetable oil will fall (soybean oil and vegetable oil are substitutes).

Answer to the supplementary question: In fact, the price of crude oil cannot directly affect the price of soybean futures. Soybean futures prices fell with crude oil prices, both of which occurred in the current financial crisis environment, so the real reason is the current lack of market confidence.