新prep2-160

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

这道题答案为C 我选择了B。

是不是这里用According to 的问题？我感觉B时态和结构都可以接受。

清楚了~几个单词不熟造成理解困难。谢谢