A．把下列句子改成祈使句。
1. You can not smoke here.                                                                  
2. You must not look out of the window.                                               
3. You may let the children play the piano.                                              
B．把下列句子改成感叹句。     
1. It is a tall tree.                                                                                  
2. They are working very hard.                                                              
3. It is very nice to see you.                                                                   
C．改同义句。         
1. What's the price of your English book?                               is your English book?       
2. My bike is broken.                                                   is              with my bike.      
3. Can I help you?                                         What              I             for you?      
4. Are these your pens?                                  Are these                            ?