A young woman in her 20s was sitting on the train, next to her mother. They both looked tired __1__ excited.
The young woman was looking out from the train's window. Suddenly, she shouted, “Mom, look, the trees are behind us！” Her voice was so __2__ that everyone on the train heard.
Mom smiled. But a young couple sitting nearby __3__ the young woman's childish behavior (行为) with pity. “Poor young woman. There must be something wrong with her __4__，” they thought.
A while later, the young woman __5__ again, “Mom, look! The clouds are running with us！”
