s. of questionable or minimal quality
n. 边界, 界线
a. 边界的
1. She is on the borderline between happiness and sadness.
她在快乐和悲伤之间徘徊。
2. The doctor said his condition is borderline and needs monitoring.
医生说他的情况在边缘状态，需要监测。
3. The school has strict rules about borderline behavior.
学校对边缘行为有严格的规定。