Some of the suggestions have been adopted ______ others turned down as they are quite impracticable.
【正确答案】 C
【答案解析】解析：本题考查前后语句的逻辑关系。前面说有些被采纳了，后面说其他的被拒绝了，这是两种相反的结果，所以应该用转折连词but。