12Unit834构成由动词原形加-ing构成时态和语态的变化5功能动词的-ing形式及其短语可以在句中作主语,宾语,表语(统称动名词),定语,补足语和状语(统称现在分词)。否定式由not加动名词组成6Learningisdifficultbutinteresting.Wavingone’shandistosay“Hi”or“Goodbye”.Learninghowtoapologizeisimportantininternationalcommunication.Walkingisgoodforhealth.Seeingisbelieving.Readingaloudisveryimportantinlearning...