土壤是由哪些物质组成的？土壤和土壤肥力的概念是什么？
参考答案：
土壤是由固体、液体和气体三相物质组成的疏松多孔体。
句型转换，每空一词。
1. We have a new computer in our classroom. (改为一般疑问句)
_______ _______ _______ a new computer in your classroom?
2. Mr Wang has a great sports collection. (改为否定句)
Mr Wang _______ _______ a great sports collection.
3. My tennis racket is under the desk. (对画线部分提问)
_______ _______ your tennis racket?
4. Jack is in our school sports club. (改为否定句)
Jack _______ _______ our school sports club.
5. Judy has some good friends. (改为一般疑问句)
_______ Judy _______ _______ good friends?
市场经济条件下，我们对“义”与“利”的态度应该是______。
A．见利思义 B．先利后义C．见利忘义 D．无利不干
