| —Why does the Lake smell terrible? —Because large quantities of water ______. A．have polluted B．is being polluted C．has been polluted D．have been polluted |
| —Why does the Lake smell terrible? —Because large quantities of water ______. A．have polluted B．is being polluted C．has been polluted D．have been polluted |
| D |
| 考查动词时态、语态和主谓一致。根据前一分句可知所填动词表示过去发生的动作对现在产生的影响，时态用现在完成时，动词与主语是被动关系，用被动语态。主语是large quantities of water，其中心词是quantities，是复数，谓语动词用复数，选D项。 |