The discus used in track competition was once designed having its weight concentrated in a metal center and now lined with lead around the perimeter, thereby improving stability in flight and resulting in longer throws.
语法 Sentence Correction-115
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正确的用户笔记
许大别扭 2014-04-09 11:39:43
design固定搭配，没有design doing的结构；having concentrated 完成时使用没必要；后半句没有谓语动词，and now 应该为and now is 时态改变，因此不能直接并列，前半句使用的是过去时态was
liqijie3242656 2014-08-09 18:24:49
fragment少谓语
ypheroin 2016-01-18 16:35:52
and now lined 没有谓语动词 design doing 不对。
liqijie3242656 2014-08-09 18:25:21
没有design doing用法
jjxxbbmm1234 2014-01-19 10:38:31
平行结构，and前为was once designed，后面为now lined,不平行，应该为is now lined
