北京拓大孝 现代远程教育 l.介词短语作表语 He is at his best in classical works. 他最擅长演奏古典作品。 We are behind the schedule now. 我们比计划的时间晚了。 We know what they are after. 我们知道他们追求的是什么。 Who is on duty today? 今天谁值班？ III.介词短语作表语 He is at his best in classical works． 他最擅长演奏古典作品。 We are behind the schedule now． 我们比计划的时间晚了。 We know what they are after． 我们知道他们追求的是什么。 Who is on duty today? 今天谁值班?