孩子们兴奋地喊着'呜呜'，模仿火车的声音。

The children happily shouted '___choo ___choo' to imitate the train sound.

宝宝兴奋地指着远处的火车喊：“看，小火车！”

The baby pointed excitedly at the distant train and shouted, "Look, the little ___choo choo!"