It is estimated that ，currently, about 50，000 species become _____every year ．
更新时间:2024-11-24 06:06:42 A、extinctA
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设数列 {an} 的前 n 项和为 Sn，则 {an} 等差。
(1) S n4=n 2+2n, n=1,2,3
(2) S n4=n 2+ 2n +1,n=1,2,3
Afterhisuncledied，theyoungman_____thebeautifulestatewithwhichhechangedfromapoormantoawealthynoble．
After his uncle died ，the young man _____the beautiful estate with which he changed from a poor man to a wealthy noble ．
TheopportunitytoexploreandplayandtheencouragementtodosoCan________theperformanceofmanychildren．
Theteamplayedhardbecausethechampionshipofthestatewas______.
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