题目

She chose one of the mostexpensive dresses in the shop and handed it to an assistant who it for her as quickly as possible. ( 根据句意填空) 答案：【1】wrapped up已知磷酸分子()中的三个氢原子都可以与重水分子(D2O)中的D原子发生氢交换。又知次磷酸( H3 PO2)也可与D2O进行氢交换，但次磷酸钠(NaH2PO2)却不能与D2O发生氢交换。下列说法正确的是A. H3 PO2属于三元酸 B. H3 PO2的结构式为C. NaH2PO2属于酸式盐 D. NaH2PO2溶液可能呈酸性