A. economic B. historical C. political D. educational
A. found B. establish C. build up D. set about
A. 子午线轮胎 B. 体育上用的发令纸 C. 拖拉机专用轮胎 D. 鞭炮焰火
A. it's B. their C. its D. theirs
A. standards B. levels C. point D. period
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