it may now be too late to clean up the river没怎么理解
having suffered such heavy pollution already ,it may now be too late to clean up the river
我认为it may now be too late to clean up the river应该被还原为
to clean up the river may now be too late 那么主语应该是to clean up the river 这句话就错误了
我想知道怎么看出逻辑主语是river
越详细越好,谢谢