she_____the blackboard before the teacher arrived.A,had cleaned B,cleaned C,has cleaned D,cleans

she_____the blackboard before the teacher arrived.A,had cleaned B,cleaned C,has cleaned D,cleans
she_____the blackboard before the teacher arrived.A,had cleaned B,cleaned C,has cleaned D,cleans

she_____the blackboard before the teacher arrived.A,had cleaned B,cleaned C,has cleaned D,cleans
答案A
这里有两个动作,
1,擦黑板
2,老师到来
我们看先后顺序,这里要表达的是在老师来之前已经擦好了黑板
老师来,是一般过去时态
所以,擦黑板就是过去的过去,就是过去完成时态

A,had cleaned

A
老师来到黑板前。这已经是过去的动作。她擦黑板是在老师之前的的动作。所以是过去的过去。用过去完成。所以是A