按要求写句子。     

1．沉迷于网络游戏会导致视力严重下降。     

改为疑问句：                                                                                

改为双重否定句：                                                                          

2．桑恩传过来紧急救援中心的电话号码。   

改为“被”字句：                                                                                      

改为“把”字句：                                                                                      

3．我上网查到许多学习资料。   

改为设问句：                                                                                              

改为反问句：                                                                                               

在政治上，元朝统治者始终奉行民族压迫政策，他们把国民分为（）四个等级。