Motion to and fro, or up and down, as on a balanced plank.

来回动；上下动。

A plank balanced on some support, enabling those who sit at the ends to move up and down alternatively.

跷跷板。

To move up and down or backward and forward.

上下动；前后动；玩跷跷板。

Vacillate.

【喻】动摇；犹豫；踌躇。