there was no need to keep it secret,in fact ,he____it when i explained it to himAwas knowing Bhas known Cwould knew Dhad known

there was no need to keep it secret,in fact ,he____it when i explained it to himAwas knowing Bhas known Cwould knew Dhad known
there was no need to keep it secret,in fact ,he____it when i explained it to him
Awas knowing Bhas known Cwould knew Dhad known

there was no need to keep it secret,in fact ,he____it when i explained it to himAwas knowing Bhas known Cwould knew Dhad known
D,这个题表示我解释给他听的时候他已经知道了,要表达过去的过去,所以用过去完成时

答案：D
解释：know 指一动作在explained 之前发生，所以用过去完成时，结构是：had + 过去分词。
祝你新年快乐，学习更上一层楼！请记得采纳，谢谢！(*^__^*)