17．听第10段材料，完成第15至17小题．
15．What is wrong with the boy？
A．He has a sore back．
B．He has a headache．
C．He has a cold．
16．Why does the boy often wake up at night？
A．He often has dreams．
B．It's noisy outside．
C．He's worried about his study．
17．What does the boy usually do before he goes to bed？
A．He swims for an hour．
B．He has something to eat．
C．He has two cups of coffee．
