题目

She might have been in time for the train, but she _______late. A. started B. has started C. was to start D. had started 答案：A 解析: 她本来或许会来得及赶上火车，但是她出发晚了。本句but以前是虚拟语气，而but后面的句子表示的是真实的事实；从might have been判断谈论的是过去的事情，所以要用过去时A。已知上海到美国洛杉矶的海底电缆共有15个接点．某次从上海发出一个信息时，某个接点发生故障，为了尽快断定故障发生点，排除故障，至少需要检查的接点个数是（ ）A．3B．4C．5D．6