The mother and 14-year-old girl took turn carrying the 4-year-old during a month-long journey.

英訳に間違いが有れば正してください。

一ヶ月に及ぶ旅の間、母親と14歳の女の子は交代しながら4歳の子供の面倒を見ました。
The mother and 14-year-old girl took turn carrying the 4-year-old during a month-long journey.

ヒント
交代

答え turnをturnsにする

The mother and 14-year-old girl took turns carrying the 4-year-old during a month-long journey.