单选题 —I wonder______Mr. Black changed his mind to take part in the movement.—After he listened to the speech by Mr. King.

A、 when was that it
B、 when was it that
C、 when that was
D、 when it was that

【正确答案】 D

【答案解析】解析：考查强调句。句意：——我不知道布莱克先生是在什么时候改变了主意去参加那次活动的。——在他听了金先生的演讲之后。特殊疑问句的强调句型：被强调部分(通常是疑问代词或疑问副词)+is／was+it+that／who+其他成分?此句中强调when，且强调句为宾语从句，故用陈述句语序。此句用非强调句表达为：I wonder when Mr Black changed his mind to take part in the movement．