用超声波法判断桩内缺陷的基本物理量有（）A.检测孔数 B.声时值 C.波幅值 D.频

A group of fifteen-year-olds at Sunshine School are holding a charity sale to raise money to help their classmate Lisa. Lisa had cerebral palsy(大脑性瘫痪）when she was a baby. Although Lisa has to use a wheelchair to help her get around, she never gives up. And she is always ready to help others. 、
Lisa has the chance of standing up, but she needs an operation(手术）which will cost lots of money." Lisa’s doctor said.
"I never thought that I could stand up one day. Actually the news is surprising for me. However, when I see my parents are worried about the cost of the operation, I am sad. I am used to my life. I don’t mind even if I can’t stand up," Lisa said, "Now ray classmates and some other kind people are helping me. I am really thankful. If I stood up one day, I would try my best to help more people."
"While helping Lisa, we can also learn a lot. We have learned how to cook cookies and how to sell them," Betty, one of Lisa’s classmates said. "Now we know making money is not easy, so we won’t waste money anymore."
Alex, a boy in Lisa’s class, told a reporter that they could raise about $100 every day. "We have raised about $2,100 so far. We hope we will raise more money for Lisa’s operation," said he.

Lisa is a fifteen-year-old girl with cerebra palsy. She can’t stand up and has to get around in a wheelchair. If she is小题1:an operation, she may be able to stand up. Bui her 小题2:have trouble affording the operation. Some kind people give her a hand and Lisa’s 小题3:   decided to raise money to help her by selling home-made cookies. After about three 小题4:  they have raised about $2,100 for Lisa’s operation. Lisa is very thankful. And she is very lucky because so many people are helping 小题5:.