问题
选择题
Mr Green didn’t know ______ last night.
A．when does his son come back
B．when his son comes back
C．when his son come home
D．when his son came home
答案
答案：D
动词know后跟的是一个宾语从句，要用陈述句的顺序，故A不正确，主句是过去
时，从句要用过去时一种，只有D用的是过去时，故选D。