下列各项属于公民对社会应该履行的义务有（）
①遵守公共秩序 ②尊重社会公德 ③爱护公共财物 ④积极见义勇为
A：①②③④
B：①②③
C：②③④
D：①②④
— Do you think yesterday's math problem was very difficult?
— Yes. I could ________ work it out.
— What colour is it?
— _____________.
