n a plaything consisting of a board balanced on a fulcrum; the board is ridden up and down by children at either end
v ride on a plank
v move up and down as if on a seesaw
v move unsteadily, with a rocking motion
n. 跷跷板, 上下动( seesaw的名词复数 )
v. 使上下（来回）摇动( seesaw的第三人称单数 ); 玩跷跷板, 上下（来回）摇动