问题
选择题
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
答案：B
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。