follow作跟着解时，为静态动词。不用进行体。例如：

Tom is walking along the road, and his dog follows him.

follow作跟踪解时，为动态动词，如果动作没有结束，就需要用进行体。

Tom is walking along the road, and a man in black is following him.

所以，作跟着、跟随解时，过去分词只表示被动意义，没有完成意义。

Followed by a dog, he came into the classroom.

他进入教室的时候，狗还是跟着他。

Being followed by a man in black, she went into the market.

被一个黑衣人跟踪者，她进入了市场。