weak pressure gradient

例句：

1. 1. Theold man is weak and needs to restmore often.
   老人身体虚弱，需要经常休息。
2. 2. The team's performance was weak inthe crucial match.
   球队在关键比赛中表现不佳。
3. 3. The baby is weak and needsextra care.
   婴儿身体虚弱，需要额外的照顾。