蹒跚后退

tiltering boards───倾斜板

run backwards───向后跑

tiltering board───倾斜板

know something backwards───了如指掌

bend over backwards───拼命

greeting cards───贺卡；贺年片

lean over backwards───走另一极端

They shuffled backwards and forwards teetering on the splintered wood as they playfully tried to show who was boss.───它们在摇摇晃晃的树干上前前后后厮打着，既像是在玩耍又像是在证明谁才是老大。