Meanwhile,a number of university students have volunteered t

来源：学生作业帮编辑：百度作业网作业帮分类：英语作业时间：2024/04/28 20:57:19

Meanwhile,a number of university students have volunteered to drive buses while the strike lasts.
在本句中have volunteered是不是现在完成时?如果是,为什么要在这儿用,而不用原型或过去式?表达了了现在完成时中哪个意思?
我看现在完成时的语法讲解，主要是1持续，2完成，3经验，在这里表达的是哪种用法，为什么会这么用，不能用其它时态吗？

是的,此处使用的是现在完成时,表示动作已经发生在过去的某一时间,使用完成时是为了表示影响,该用法的现在完成时表示一个过去发生的动作在过去已经完成,并且这个过去发生并完成的动作对现在有影响或结果,同时说话者强调的或感兴趣的就是这个影响或结果.

Meanwhile,a number of university students have volunteered t a number of students还是a number of the students a number of the students An increasing number of students have r Do university students have a lot of homework?What is your a A number of students,请问 A number of 与the number of students有 a number of students in hongshanhu have to take a boat to ge The number of the students of the university ____ more than "The number of the students of the university ____ more than 选择：A number of students _____ come 麻烦老师解答：A number of students 在线求指导：A number of students