{{B}}第一节{{/B}} 听下面5段对话。每段对话后有一个小题，从题巾所给的[A]、[B]、[C]三个选项中选出最佳选项，并标在试卷的相应位置。听完每段对话后，你都有10秒的时间来回答有关小题和阅读下一小题。每段对话仅读一遍。 What has happened to steam trains [A] They have been replaced by electric trains.[B] They have been used for special railway service.[C] They have become more comfortable.