at source

例句：

1. 1. The investigation revealed the true atsource of the problem.
   调查揭示了问题的真正起因。
2. 2. The company's decision wasbased on a misunderstanding of theat source.
   公司的决策是基于对起因的误解。
3. 3. The scientist discovered the at sourceof the disease in the patient'sdiet.
   科学家在病人的饮食中发现疾病的起因。