his eyes flashing about restlessly是独立主格结构，也就是所谓分词复合结构，在句中做状语，表伴随。意思是：他这样说，双眼不安逸地到处游移。
§分词做状语时，逻辑主语就是句子的主语。 也就是说，主语发出分词动作时，用现在分词，当主语承受分词动作时，用过去分词。如：Carrying a pen in her hand, the girl was thinking about a maths problem.
Carried by its mother, the baby stopped crying.
§当句子的主语既不发出分词动作也不承受分词动作时，需在分词或分词结构前加上其逻辑主语，这种复合结构就叫做独立主格结构。如: Some friends sitting around her, the woman was telling about her husband’s betray.
It being Sunday, students were free from their classes.
Father beating the son, mother went to her parents’ home.
Father arrested, the whole family was deeply depressed.
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