题目

I have a special place in my heart for libraries. I have for as long as I can remember. I was always an enthusiastic reader, sometimes reading up to three books a day as a child. Stories were like air to me and while other kids played ball or went to parties, I lived out adventures through the books I checked out from the library.My first job was working at the Ukiah Library when I was 16 years old .It was a dream job and I did everything from shelving books to reading to the children for story time.As I grew older and became a mother, the library took on a new place and an added meaning in my将两种溶液混合有白色沉淀生成，加入稀硝酸，沉淀消失，且有气体生成，再加入硝酸银溶液，又有白色沉淀生成，则这两种溶液是： [　　]