[A] «worked,» «loved» [B] stolen money; a written report; fallen trees; broken glass; tired drivers; blocked roads. He has seen; to have loved; it was broken. She enters. She is accompanied by her mother = She enters, accompanied by her mother; He was aroused by the crash and leapt to his feet = Aroused by the crash, he leapt to his feet; The bridge had been weakened by successive storms and was no longer safe = Weakened by successive storms, the bridge was no longer safe, o bien «Having being weakened etc.; As he was convinced that they were trying to poison him, he refused to eat anything = Convinced that they were trying to poison him, he refused to eat anything. Having been warned about the bandits, he left his valuables at home. («He had been warned» etc.); Having been bitten twice, the postman refused to deliver our letters unless we chained our dog up. («He had been bitten» etc.)
[[A] Forma: El participio de pasado de los verbos regulares se forma añadiendo ed o d al infinitivo. [B] Uso: como adjetivo; para formar los tiempos de perfecto, los infinitivos o participios de perfecto y la voz pasiva; para reemplazar a un sujeto + verbo pasivo de la misma manera que el participio de presente puede reemplazar a un sujeto + verbo activo. El participio de perfecto pasivo (having been + participio de pasado) se emplea cuando es necesario enfatizar que la acción expresada por el participio sucedió antes que la acción expresada por el siguiente verbo.]
A Practical English Grammar (A.J. Thomson & A.V. Martinet) 