题目

 I hadn’t even got a chance to enter the store before an African American woman approached me and asked if I would help her return an item. The item she has ___36__ was intended for her daughter, but she had already received a similar one. The lady ___37__ to exchange the item for something else in the store but she was told she needed an ID or the deal could not take place.   I went to the __38__ with the woman so we could use my ID. The sales associate immediately started ___39___ her of asking the first random person she saw to help her. Although that was _40__ , I didn’t unde跟Na、Na2O、Na2O2、NaOH、Na2CO3、NaHCO3六种物质都能发生反应的是（   ） A．H2O       B．CO2               C．Ca（OH）2            D．H2SO4