题目

It was raining heavily. Little Mary felt cold, so she stood ______ to her mother.    A. close                    B. closely                  C. closed                 D. closing 答案：A 解析: 略下列物质中，既含有离子键，又含有共价键的是 A．NaOH            B．H2O              C．Na2S             D．CaCl2