我觉得很好理解啊,就是和进行时的理解差不多
不定式进行式表示动作正在进行,通常与限定动词表示的动作同时发生.
例：
He seems to be following us.(=It seems that he is following us.)
She pretended to be listening attentively.(=She pretended that she was listening attentively.