用作优质钢冶炼气,H2S含量小于()。
参考答案:
1-2g/m3
—Miss White, what's wrong with my mother?
—Don't be _ _ about her. She is better now. [ ]
A. worry
B. worrying
C. worried
矿物元素是动物营养中的一大类营养素,广泛分布于体内各个组织、器官,占畜体的()。
A、1~2%,
B、3~5%,
C、6~10%,
D、11~15%。