weak boundary condition

例句：

1. 1. The old man was weak from lack of sleep.
   老人由于缺乏睡眠而身体虚弱。
2. 2. The team's performance was weak in the crucial match.
   球队在关键比赛中表现不佳。
3. 3. The new drug is said to have a weak effect on the heart.
   据说这种新药对心脏的影响很微弱。