过去完成时表示过去某一时刻或某一动作之前已完成的动作或状态(亦可以说是“过去的过去”)。过去完成时由had加过去分词构成。
过去完成时疑问句句型:Had + 主语 + 过去分词...?
回答方式:Yes,主语 + had.
No,主语 + had + not.
过去完成时的疑问句是将助动词had置于主语之前(大写had的第一个字母),在句尾加问号;这种语序是倒装语序:
例句1:I visited the museum yesterday.—Had you visited it before?
—Yes,I had./No,I hadn't.
例句2:Had he finished his homework before he went out to play ?
例句3:Had l bought a car before l got money?