单项选择题
A.not yet using postage stamps B.collecting valuable stamps C.buying stamps from Neuritis D.printing their own stamps
A.The "Post Paid" Error B.The Two Penny Blue C.A Rare Stamp D.How Mauritius Became Famous
A.the One Penny Orange-Red B.a correctly printed'1847 stamp C.the Two Penny Blue D.both A and C