Observational studyaims at the approach to a dynamic system whose equation is undeterminable.

该方程组解在有限时段上采样值与给定序。

He recalls a mother in her late 20s who came to him because she had an inoperable defect in her aorta that would rupture at some undeterminable time in the future, killing her instantly.

“我认为，激烈面情绪有这样，它可以使我们正常活动停止，以便我们可以在一段时间内专注于某些事物”，他这样说到。