问题详情

Passage ThreeQuestions 32 to 35 are based on the passage you have just heard.32.
A. The workers on the underground platfonns were replaced by machines.
B. It became the first completely automatic railway in the world.
C. A completely automatic line was added to its network.
D. Its trains became computer-controlled.请帮忙给出正确答案和分析，谢谢！