问题补充：
The teacher left word with our monitor she would explain the problem again next time.
A. who
B. which
C. as
D. that
答案：
A. who
B. which
C. as
(答案→)D. that
解析：考查同位语从句。本题中的同位语从句that she would explain the problem again next time是对前面的名词word的内容进行解释说明，that在句中不充当任何成分，只起引导作用。故D正确。
