n.泡泡纱
There was a sandpit, a seesaw and a swing in the playground.
游乐场上有一处沙坑、一块跷跷板和一个秋千架。
Prices have gone up and down like a seesaw this year.
今年的价格像跷跷板一样时涨时跌.
Marriage, however, is an emotional seesaw.
然而婚姻是一块感情跷跷板。