Being+动词过去分词强调正在被。。。时用。Being interviewed ,he felt very nervouse .done放在句首时表示：被动，完成或状态 。Seen from the top , the building is very high .worn out after a long walk , he felt very tired .Having done 放在句首表示该动作与主句的主语是主动关系且强调该动作发生在主句谓语动作之前。Having finished his work ， he went home happily ....
