3. Playing computer games waste parents’ hard-earned money. 这句话是经典的主谓不一致的错误。主句是playing computer games 动名词做主语,所以谓语动词要用单数加s。在写一个现在时的句子时,一定要注意主谓一致问题。主语是否是可数名词单数、不可数名词、动名...