Definition (医疗)
When a part of your body is in a cast, it means that it is encased in a plaster cast to protect a broken bone while it heals.
打了石膏（保护受伤处）
He has a leg in a cast after breaking it while skiing.
他在滑雪时摔断了腿，现在腿上打了石膏。
She had to have her wrist in a cast after fracturing it.
她手腕骨折后必须打石膏。
The doctor said his ankle would need to be in a cast for six weeks.
医生说他的脚踝需要打石膏六周。