We（）the distress signal on our own radio before the shore station relayed it to us.

A.received alreadly

B.have received

C.had received

D.was receiving

近年来，国内发生余祥林、赵作海等一系列冤案，在社会上引起广泛关注和热烈讨论。一位学者认为，冤案形成的主要原因在于司法权缺乏有效监督。
请结合上述材料，试分析我国法律监督的现实意义。