【题目】He stayed there for quite a long time, during_______ time he learned much spoken English.
A.that
B.this
C.which
D.the same

【答案】C
【解析】考查定语从句。句意：他呆在那里好长时间，期间他学了许多口语英语。因在介词后不能用that来引导定语从句，所以选C。