【查阅资料】：

①在同等条件下，碳分子筛对不同气体的吸附强度不同，如图2所示；

②碳分子筛可以再生，能重复使用．

下列物质属于纯净物的是(  )

我国西北内陆气候干旱，形成大面积戈壁和沙漠的原因是（  ）

根据句意及汉语提示完成单词.

① Have you____ (曾经)taken the subway alone late at night?  

②She won first____ (奖)in the 100-meter race.  

③It was his____ (梦想)to play football for his country.  

④We can not____ (付得起)the cost of two telephones.  

⑤It was a____ (遗憾)that you missed the party.  

能克服远缘杂交不亲和障碍的技术是(    )