根据下列短文内容，在短文后的空格处填上一个恰当的词，使短文完整、通顺。
Stamp collecting is a popular 1 . I like collecting stamps. Most of my stamps are 2 France,
Canada, Russia and the USA. I know I can't 3 stamps from every country because there are too
many.
I don't buy any stamps because they 4 too much money. My father often goes to other counties
for work, so he can 5 foreign stamps home. If I don't like a stamp, I try to change it with others.
Most of my stamps are used (用过的) 6 . I have to get the stamps off the envelopes (信封). I put
the envelopes into a bowl of water. After a few minutes the water makes the envelopes 7 . Then it's
8 for me to peel off (剥落) the stamps. After that, I let them dry and put them in my stamp album.
My stamps make my school subjects interesting. They 9 me what animals, plants, mountains and
rivers there are in a country. It is helpful for my study. 10 some of my stamps will become valuable
someday.
