根据汉语提示，结合句子意思，在横线上写出恰当的单词或词组。
1. Some people _______ (当作) the pets as their family members.
2. Next year the _______ (二十九) Olympic Games will be held in Beijing.
3. It is not easy for me to finish the work _______ (独自) in such a short time.
4. Thank you very much for sending me so many wonderful _______ (邮票).
5. Not many families can afford to send their children _______ (出国求学).
