题目

下列物质的用途，主要利用其物理性质的是（    ） A.氧气用于炼钢  B.干冰用作制冷剂 C.一氧化碳用于炼铁  D.熟石灰改良酸性土壤 答案：BThey got married_______ 1960. That means they have been married _______ 1960.A. at; since B. on; in C. in; since D. for; since