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．there are few others like it B．there are no errors on the stamps C．a mistake is made in the ,printing D．both A and C