被减数-差=24,可知减数是24,
被减数:30+24=54,
减数是被减数的:24÷54=49.
故答案为:正确.
汶川地震后,为支援灾区防疫,某厂紧急生成过氧乙酸消毒液,过氧乙酸化学式为C2H4O3,以下说法正确的是( )
A.过氧乙酸由C、H、O三种元素组成
B.一个过氧乙酸分子由8个原子构成
C.过氧乙酸是氧化物
D.过氧乙酸是混合物
In the nineteenth century, poor Europeans seeking to make their fortunes turned to America as a matter of course .
A.automatically
B.obviously
C.traditionally
D.resignedly