题目

104 John: Do you happen to have twenty dollars with you?  Jack: _______ John: I want to buy a notebook. A. How do you want it?  B. How much? C. What for?     D. When can you pay me back? 答案：C地衣生活在岩石上，可以从岩石中得到所需要的营养物质，地衣又能够分泌地衣酸，使岩石分解成为土壤。这一事实说明____       ______。