BY 1820, THERE WERE OVER SIXTY STEAMBOATS ON THE MISSISSIPPI RIVER, __...

158: - 600 CAU TRAC NGHIEM TIENG ANH
600 CAU TRAC NGHIEM TIENG ANH
158: By 1820, there were over sixty steamboats on the Mississippi river, _______ were quiteluxurious.A. which many B. many of them C. many of which D. many that