The man we met yesterday may be jogging in the park now.

含有情态动词的完全倒装，如果是进行体，只把现在分词短语提前句首，may be 位置不变：

Jogging in the park now may be the man we met yeasterday.

（现在分词+地点状语 + may/can be + 主语）

倒装的原因是由于句子主语太长而后置，以保持句子匀称，属于修辞范畴。

In the park may the man we met yeasterday be Jogging now. （这句话违背了语言表达的基本要求，是错误的）

不含情态动词的进行时的完全倒装：

Mary and David were sitting in front of the house.

--Sitting in front of the house were Mary and David.

-- In front of the house were sitting Mary and David.