n.标题；题目；航向
动词head的现在分词.
The heading was in large letters. 标题是用大号字母印刷的。
Choose a descriptive subject heading. 选择适当题目。
Imagine, too, that you are heading for the Arctic. 想像你正要航向北极，而且需要带五枚照明弹到达目的地。
Maintain present heading for a while. 保持一会儿现在航向。
