动名词现在分词作状语的区别

、现在分词短语作时间状语有以下三种情况：1．分词动作一发生,谓语动作紧跟着发生,这时用现在分词的一般式作时间状语,其逻辑主语为句中的主语。常用的动词,如：hear,see,arrive,return,get to,look,open,close,leave,turn around,walk等,表示一个极短暂动作。此种情况可以换作on+动名词,表示相同的意思。译作"一（刚）……就……"。此种情况也可以换作是when引导的时间状语从句,该从句的动词多用一般过去时表示。如：Hearing their teacher's voice,the pupils stopped talking at once。（= On hearing their teacher's voice… = When they heard their teacher's voice,the pupils…）一听到教师的声音,学生们立即停止讲话。2．谓语动作发生在分词所表示的动作过程之中,则用when /while+现在分词的一般式,分词的逻辑主语为句中的主语。此种情况可以用in+动名词的一般式代替。也可以换作when、while引导的时间状语从句,该从句的谓语动词用进行时态。如：Don't be careless when /while having an exam。= Don't be careless in having an exam。= Don't be careless when / while you are having an exam。考试时不要粗心。注：此结构中,不能用其他连接词替换when或while。3．分词所表示的动作完成之后,谓语动作才发生,则要现在分词的完成式,即having done的形式。分词的逻辑主语应是句中的主语。这种情况可以用after+动名词的一般式表示。这种情况也可以用after /when引导的时间状语从句来替换,该从句的谓语动词用过去完成式。如：Having finished his homework the boy was allowed to watch TV play。After having finished his homework,the boy… After /when he had finished his homework,the boy…