前仰后合
qián​yǎng​hòu​hé HSK7

to rock back and forth

  1. 前 qián locativenoun
    front
    (bound form) front; forward; ahead; facing direction. Use 前边 qián​bian or 前面 qián​miàn for the standalone noun.
  2. 仰 yǎng verb
    to look up
    To face upward or look up; the opposite of 俯 fǔ
  3. 后 後 hòu locativenoun
    behind
    (bound form) back; rear; behind; in the direction of one's back
  4. 合 hé verb
    to join
    to close; to shut; to join; to combine; to pool (efforts, etc.)