春秋战国时期，私营工商业勃然兴起的主要原因是
①生产力的提高   ②生产关系的变革   ③农民身分的提高   ④人口的大量增加

句型转换
(1)Betty did very well in her English exam . (改为否定句)
____                                                 
(2)It's ten minutes' walk from my home to school.(划线部分提问).
____                                          
(3)Where does Jim study? I want to know. （合并为一句含有宾语从句的句子）
____                                                    
(4)You have to eat little meat, ____ ？ （写出反义疑问句）
(5)They clean their classroom after school every day . （改为被动语态）
____ 

— Oh, yes! It's down the street.