敲击拉伸的弹簧发出的声音，要比敲击自然状态下的弹簧发出的声音（  ）

【环境保护】2015年3月31日，甘肃敦煌遭遇强沙尘暴袭击，能见度不足20米。世界文化遗产莫高窟暂时关门谢客。下图为敦煌近30年平均沙尘暴四季分布比例图。读图回答下列问题。

阅读下面短文，根据短文内容回答问题。

    My name is Grace. Today is Sunday. It is a nice day. It is also my grandfather's birthday. He is 80 years old. My parents and I go to his home. We don't get up early because the alarm clock (闹钟) doesn't work. We don't have much time for breakfast. We go to a supermarket to buy some fruit and a birthday cake at eight thirty. Then we go to my grandparents' home quickly. We get there at 11:15. My grandparents are very happy to see us. We have lunch at 12 o'clock. After lunch, we play chess with my grandfather. It is interesting. We go home at about four o'clock in the afternoon. It is a happy day.