1. We'd like to buy some oranges. (改为一般疑问句)

2. This French book must be Mary's. (改为否定句)

3. It seems that she has changed a lot. (改为同义句)

4. Why don't you join an English club to practice speaking English? (改为同义句)

5. It is so hard that we can't understand the sentences. (改为简单句)