根据句意和汉语提示写出单词，完成句子。
1. Ketty will go (在国外) as an exchange student.
2. I’d like to buy the nicer one of the two (牙刷).
3. There were twenty people in the room, (包括) the teacher.
4. He often doubts (是否) it is worth working so hard.
5. Sichuan Ya’an had an earthquake on April 20, 2013. Now many (急救的) things are needed there.