宝宝指着窗外兴奋地喊：“看，小火车！”

The baby pointed outside and shouted excitedly: "Look, the ___choo-choo!"

孩子们开心地模仿蒸汽火车的声音，'呜呜'地叫着。

The children happily imitated the sound of a steam train, shouting '___choo-choo'.