Please complete the summary of paragraphs C and D below.
请完成下面 C 和 D 段的总结。
DDay is celebrated to memorize the Normandy landings in France on June 6, 1944.
D 日是为了纪念1944年6月6日在法国的诺曼底登陆。
Foods such as eggs and oily fish are all rich in vitamin D.
鸡蛋和油性鱼等食物都富含维生素D。
Three other types of airspace, Classes D, C and B, govern the vicinity of airports.
其他三种领空，D、C 和 B 类，管理着机场周围地区。
The Ph. D. candidate is likely to change his field of specialization if he drops out.
如果这位博士候选人退出，这很可能会改变他的专业领域。
Theodore and Franklin D. Roosevelt, William Howard Taft, Dwight D. Eisenhower, Lyndon B. Johnson, Gerald Ford, and George H. W. Bush all had offices in this building before becoming president.
