15．A） The class teacher missed the morning meeting． B） The class teacher was looking for the boy all morning． C） Alice was having a morning meeting on"how to keep the classroom clean"． D） Some plans on"how to keep the classroom cle an"were discussed at the meeting．
5．A．What's the highest mountain in the world？ B．Why do so many people climbers risk their lives？ C．A few weeks ago，I found the marks of another man's feet on the sand．
