是名词、动词和助动词,例如:1、This will be a problem for some time to come.这将是未来一段时期里的一个问题。2、The new model will be in production by the end of the year.新型号将于年底投产。3、Your duties will include setting up a new computer system.你的职责将包括建立一个新的计算机系统。