—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 答案:D读下图,回答1—2题。 1、选择坝址是修建水库的关键之一。图中所示方案中,构造稳定、地基坚实、最适宜建坝的是A、① B、② C、③ D、④ 2、图中四种地质构造不是由水平挤压运动形成的是 A、① B、② C、③ D、④