22. You have to explain ______you were absent from school yesterday.
A
what
B
which
C
where
D
why
根据题意，此处是宾语从句，此处与explain搭配的应该是原因，因此引导词用why。 故选D..
本题是语法知识题。本句意思是：你必须解释昨天你为什么没来学校。此处选D.
把握不准引导词。