关于过去分词heard

关于过去分词heard
what shall Ipay atteniton to when I make a speech,mother?
First of all,you should make yourself)_______
A.hear B.hearing C.heard D.to hear.
选择哪个为什么?
they ordered me to let to the traffic go again.
为什么这个地方用let to ; go 为什么不用 to let ;to go 还有啊过去分词作宾补能不能说的更详细一点啊。我对这个地方不懂啊。