题目

   Today about 70 countries use Daylight Saving Time(DST). Daylight Saving was first introduced during World War I in Australia. During the world wars, DST was used for the late summers beginning January 1917 and 1942, and the full summers beginning September 1942 and 1943. In 1967, Tasmania experienced a drought（干旱）. The State Government introduced one hour of daylight saving that summer as a way of saving power and water. Tasmanians liked the idea of daylight saving and the Tasmanian Government has declared daylight saving each summer since 1968. Persuaded by the Tasmanian G埋在地下的输油铸铁管道，在下列各种情况下，被腐蚀速度最慢的是（    ）A.在含铁元素较多的酸性土壤中B.在潮湿疏松透气的土壤中C.在干燥致密不透气的土壤中D.在含碳粒较多、潮湿透气的中性土壤中