He was studying to be a doctor.

他在读医科。

I'd bet dollars to doughnuts he's a medical student.

我敢打赌他是个医科学生。

He is a medical student.

他是个医科学生。

A survey on 155 opioid abusers and their polydrug abuse was carried out with a questionnaire designed by National Institute on Drug Dependence.

医科大学中国物依赖性研究所设的调查表,对155例阿片类者及其多情况进行调查。