D let sb be done 的结构 意思是 他们不愿意让他们的老师受到这样的对待.
let 的用法有 let sb do, let sb be done 无 let sb done/doing 的说法
比方说 朗文当代辞典中有： Don't let yourself be pushed around.（别让人摆布你）的表达.
(p.s ) have 作使役动词 have sb. do; have sb./sth. doing; have sth. done
make make sb. do; make oneself done (heard, understood)
get get sb. to do; get sb./sth. doing; get sth. done