看一篇讲述牛奶营养方面文章有一句话：
In fact, in 1985，the United StatesDepartment of Agriculture officially recommended a switch to skim milk, threeglasses of it a day. But, more recently, we've begun collecting evidence thatsays the 美元A might be missing an important piece of story.
请教大伙，这句话中进行时态be missing里的动词miss完全是一个过去的动作，语义也无需强调正在进行，为什么用进行时态呢？
并请与一些其他例句来讲明如此的表达办法?
《韦氏高阶》动词miss解释之一及例句如下，你的句子中miss就是这种使用方法。
3 [+ object] : to be without : to lack — used in the phrase be missing
He was missing one of his front teeth. [=he did not have one of his front teeth; one of his front teeth was missing]
The old house is missing some of its windows.