In the dim room, two people use different vacuum cleaners to suck a yellow doll, make a flow of air, first pair of the doll on the red vacuum cleaner, then one person put the doll on the mouth of the gray vacuum cleaner, then make a second pair of sucking, the doll still sucks on the red vacuum cleaner, the gray vacuum cleaner again sucks, the doll is still sucked on the red vacuum cleaner, one person makes a