It __________ Tom that parked the car here, as he is the only one with a car.

A．may be

B．might have been

C．must have been

D．could be

①电缆线路障碍测试一般有哪三个步骤？②电缆障碍查找的主要方法有哪些？③电缆障碍产生的原因有哪些？