1)Aliens,异形第二集2)second category,第二纲集3)the second form,第二形式4)second enrichment zone,第二富集带5)S-nowhere dense set,S-第二纲集6)the second type derived set,第二类导集
用法例句
In this paper,by using the method of set theory,we prove that the set of continuity points of the first Baire function over R~n is a second category.