Section A Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer. 听力原文：W: Mary missed her class again, didn't she? M: Well, she went to the 9 o'clock lecture that lasted for one hour, but she left when it was half over. Q: When did Mary leave? (12)