Lawrence Craven a doctor from the USA is the author of several published reports one of in

问题补充：

Lawrence Craven,a doctor from the USA,is the author of several published reports,one of introduced the idea in 1953 aspirin could reduce the risk of heart attacks.

A. them; when

B. which; that

C. what;that

D. which; when

答案：

A. them; when

(答案→)B. which; that

C. what;that

D. which; when

解析：本题同时考查非限制性定语从句和名词性从句中的同位语从句，故第一空用which，第二空用that。