239. Senator Lasker has proposed legislation requiring that employers should retain all older workers indefinitely or show just cause for dismissal.
(A) that employers should retain all older workers
(B) that all older workers be retained by employers
(C) the retaining by employers of all older workers
(D) employers’ retention of all older workers（E）
(E) employers to retain all older workers
A怎么不对,required的用法是怎么样的? | 
