题目: 服用铁剂后可排出黑便的原因是________________________________________________________________________________。 答案: 参考答案:铁与肠道内硫化氢作用生成黑色的硫化铁
题型:选择题 You can’t go out because it is a stormy night; , your homework hasn’t been done.A.moreoverB.howeverC.neverthelessD.therefore 查看答案