four不是动词,是数量词,意思是四、第四,例如:1.It is estimated the project will last four years.据估计,这项工程将持续四年。2.The child disappeared from his home some time after four.这孩子四点多的时候就离家不见了。3.She asked her students to get into groups of four.她让学生每四人分为一小组。