按要求，把句子换一种说法。    
1．一切能吃得到的绿色植物，都被饥饿的鹿吃光了。（改成“把”字句）          
                                                                                                                            
2．汤姆把大鲈鱼放回了水中。（换成“被”字句）          
                                                                                                                            
3．蜻蜓是我们的好朋友。（改成反问句）