1）_____C____,the train started.
A.After having given the signal B.After the signal given C.Giving the signal（我觉得该选B）
2）_____,so you can wait a while
A.The play is still on B.The play being still on C.As the play is still on D.The play still on （怎么我觉得B和C都行）
第1题目的C如果改为 Given 那怎么B错了呢，我觉得B也是独立主格啊