—Whydoestheriversmellterrible?—Becauselargequantitiesof...

問題詳情：

—Why does the river smell terrible?

—Because large quantities of water ________.

A．have polluted  B．is being polluted

C．has been polluted  D．have been polluted

【回答】

D　

知識點：現在完成時及其被動式

題型：選擇題