A、The talk was supposed to begin at other time. B、His secretary wouldn’t come for help. C、The guest speaker wouldn’t be able to

It was years since I had visited my hometown and I was determined to enjoy my stay. I went to see my old friend, Tom Clark who, among other things, was a member of the Local Council. At the time Tom was busy making arrangements for a distinguished writer to give a talk on modern literature at the town library. As the subject interested me a great deal, I gladly accepted Tom’s invitation to go with him.
    Tom was going to introduce the guest speaker and that evening we went to the library to meet him. Since he had not yet arrived, I left Tom and went into the Reading Room where a large audience had already gathered. I was disappointed to find that I did not know a single person there. Just before the talk was due to begin, I saw Tom waving to me from the doorway. I went to him immediately, as he looked very worried. He explained that he had just received a telephone message from the writer’s secretary. Our guest speaker had missed the train and would be unable to come!
    While we were talking about the problem, Tom suddenly asked me if I would mind acting us speaker. I hardly had time Io think about the mutter when I found I was being led into the Reading Room to address the waiting audience!