他为自己的缺席提供了一个站不住脚的借口。

He provided a ___weak excuse for his absence.

她逃课的理由很容易被驳倒。

Her ___weak reason for skipping class was easily disproved.

律师指出了对方案件中论点的薄弱之处。

The lawyer pointed out the ___weak argument in the opponent's case.