When you send a letter or a postcard, you have to put stamps on the envelope or on the card．When did people first begin to use stamps? Who was the first to think of this idea?
In the early nineth century, people did not use stamps．They had to pay postage (邮费) when they received letters．Sometimes they didn't want to receive a letter at all, but they had to pay money for it．They were unhappy about this．The postage was high at that time, because the post offices had to send many people to get the postage.
Rowland Hill was a school teacher in England．He was the first to think of using stamps in 1850s．He thought it would be much easier for people to use stamps．People could go to the post office to buy stamps and put them on envelopes before they sent the letters．The post office could just put seals (邮戳)．on the stamps so that people could not use the stamps again．In this way, the post office did not need to send post men to get postage．It only needed fewer postmen to send letters.
People began to use stamps ______.

When you send a letter or a postcard, you have to put stamps on the envelope or on the card. When did people first begin to use stamps? Who was the first to think of this idea?
In the early nineth century, people did not use stamps. They had to pay postage (邮费) when they received letters. Sometimes they didn't want to receive a letter at all, but they had to pay money for it. They were unhappy about this. The postage was high at that time, because the post offices had to send many people to get the postage.
Rowland Hill was a school teacher in England. He was the first to think of using stamps in 1850s. He thought it would be much easier for people to use stamps. People could go to the post office to buy stamps and put them on envelopes before they sent the letters. The post office could just put seals (邮戳). on the stamps so that people could not use the stamps again. In this way, the post office did not need to send post men to get postage. It only needed fewer postmen to send letters.
People began to use stamps ______.