生日派对上，孩子们开心地拍打着彩色大气球。

At the birthday party, the children happily batted the colorful ___balloon around.

孩子们兴奋地看着五彩缤纷的气球飘向天空。

The children watched excitedly as the colorful ___balloons floated into the sky.

医生使用球囊扩张了堵塞的血管。

The doctor used a ___balloon to expand the blocked blood vessel.