不得力的 meaning in English

inefficient
inept

I'm no hero, and a bad conspirator .
我不是英雄，而且是个很不得力的同谋犯。
The student was late and gave an invalid excuse .
这学生迟到了，并且做了一个不得力的辩解。
The fact of the matter is , however , that proportionate blame should be assigned to the lackadaisical approach to developing new markets , failure to improve product quality and government inaction in the realm of support
然而，事实是一部分原因应归结为开拓新市场的不得力的方法、改进产品质量的失败以及政府没有表示支持的行动。