The teacher asked the students to hand in their papers when they（ ）the test.
A、
had finished
B、
would finish
C、
would have finished
D、
were finishing
【正确答案】：A
【题目解析】：
完成考试在前，交试卷在后，由于交试卷是一般过去时，则完成考试的动作应该使用过去的过去，即过去完成时（had+动词过去分词），故选A。
句意：老师要求学生完成考试后交试卷。