At first the Monkees played and sang songs _____(write) by other musicians. 答案是written,为什么一个过去分词就可以表被动?

At first the Monkees played and sang songs _____(write) by other musicians. 答案是written,为什么一个过去分词就可以表被动? at the first crossing first of all first the first at first的区别 at the first,at first与first的区别 sign at the first desk 比较first,at first,in the first placethank you~ first of all,first,at first,for the first time,the first time有什么区别 love at first sight 还是 love at the first sight at the first 与 at first的区别 高手帮忙at first sight还是at THE first sight? at the first floor还是on the first floor in the first year和at the first year lang ling likes the bears than the monkees为什么要用better快 in the first place与at first区别 the first和at first有什么区别 辨析 first（first of all);at first;in the first place They were at the zoo at the first time 改错 at the first time t与he first at the first time t与he first time区别?