分词位于句首作状语时,其逻辑主语都是这个句子的主语.
例：Finishing his homework,he went out for a walk.
完成作业后,他出去散步了.
至于“Having +过去分词+句子,Having been +过去分词” 的句子,其用法都是相同的,只是强调的角度不同而已.单独用分词时,只强调动作的完成,不涉及对“现在”的影响,而用“Having +过去分词+句子,Having been +过去分词”时,就必须涉及到“现在”,也就是现在完成时的基本用法.
例：Having seen the film,he felt very excited.
Having been living in this city for a month,he visited many places of interest.
当然,如果是过去分词（短语）作状语,则含有被动意义.
例：Hit by a car yesterday,he he had to be in hospital.
Watered by my grandmother,the flowers in the garden look more beautiful.