Lost Underground is a story about school children who went on a trip to some caves. These caves were very large and people could go into them only with a guide. 【小题1】 ,four children decided to explore on their own. They went in the caves with a group, but left the group and walked down a tunnel. They thought it would be 【小题2】 to explore the caves alone.

Soon they came to a hole in the wall. They climbed 【小题3】 the hole into another part of the cave. Then they decided to 【小题4】 , but they could not remember the way. They were lost in the caves. When the guide led the other children out of the caves, he counted them. He discovered that there were four children missing. He had to go back into the caves to try finding the missing children.

The children who were lost moved deeper and deeper into the caves. The deeper they went, the  【小题5】 lost they became. They were  【小题6】 . They started shouting for help, but the guide didn't hear them. How dangerous they were!

Soon they came to an underground river. They guessed that the river must flow out of the caves. The water was very cold and deep, but the children  【小题7】 swimming. For a long time, they swam in darkness, then they saw light ahead of them. The river was flowing【小题8】the river on to the riverbank. They saw the bus with the other children in the distance.