【题目】He worked in a car factory for four years, ______ he founded his own company in his hometown.
A.after which
B.after when
C.after that
D.after it

【答案】A
【解析】考查定语从句。句意：他在一家汽车公司工作了四年，在那以后，在家乡建立了自己的公司，after which引导定语从句，故选A项。