PartⅣ　Exercises

1.Read and complete the blanks.

（1）Metro signaling is a________and amazing system.

（2）To prevent any train delays，accidents，even________，it is important that a________system operated by a group of well-trained people.

（3）The most important components in a metro signal system are its electromechanical________.

（4）If a metro signal________，the signaling light will go to red and the train will stop until the failures are________.

2.Translate the following passage into Chinese.

Today，metro train control is done by an Automatic Train Control system（ATC），which is a combination of three sub-systems，ATO，ATP and ATS.ATP separates train，ATS routes trains，and ATO gathers information from both ATS and ATP to directly control the trains.

The metro signaling lights work just like traffic lights for cars.Red means stop，and green means advance.The signaling lights are automatically controlled by the location of the trains.As one of the trains moves along the track，it relays on the track to send the signal of its location to the lights.A red light stays on until a leading train has moved a safe distance.