【题目】Jack had planned to visit his grandparents last weekend, but an emergency _____ and he had to reschedule.
A.should come upB.had come upC.came upD.would come up
在线课程【答案】C
【解析】
考查时态。句意：杰克原计划上周末去看望他的祖父母，但突然发生了一件紧急事情，他不得不重新安排时间。由“he had to reschedule”可知，and连接的两个句子都为一般过去时。故选C项。