写出同义句：This volunteer work takes thern several hours a week.

they spent several hours a week on this volunteer workTheyvolunteerseveral hours a week to this volunteer work .这样可以吗?好牵强的，虽然没有语法错误。但是就这个问题本身是要你变词组的一些用法的。花费时间they spend several hours a week on this volunteer work 。