标题: 求助OG12-23语法 [打印本页] 作者: doudouzhu 时间: 2010-2-18 08:21 标题: 求助OG12-23语法 23.In a previous design, the weight of the discus used in track competition is concentrated in a metal center, but now it is lined with lead around the perimeter, thereby improving stability in flight and resulting in longer throws.
(A)In a previous design, the weight of the discus used in track competition is concentrated in a metal center, but now it is
(B)According to a previous design, the weight of the discus used in track competition was concentrated in a metal center, but now it is
(C)Once designed with its weight concentrated in a metal center, the discus used in track competition is now
(D)The discus used in track competition, once designed with its weight concentrated in a metal center, but now
(E)The discus used in track competition was once designed having its weight concentrated in a metal center and now