问题
选择题
His father often comes back from work at 10 o’clock at night _______ his mother is waiting for him.
A．that
B．when
C．where
D．which
答案
答案：B
考查定语从句。定语从句的先行词是指代时间的10 o’clock，定语从句的结构很完整，故使用关系副词when。句意：他的父亲常常在晚上10点回家，在那时他的妈妈正在等着他。故B正确。