根据句意用括号内所给单词的适当形式填空：
1. A woman ______ Anna Jarvis started Mother's Day in early 1990s. (name)
2. Mr Liu says that the Internet is the most important ______ since the printing press. (invent)
3. Russia is the ______ in area and in population in Europe. (big)
4. He can ______ learn a lot about where I live. (real)
5. There is ______ metal than plastic. (little)
