根据句意和汉语注释，写出单词的正确形式。
1. Like many famous scientists, Li Siguang __________ (致力于) himself to the study of science.
2. __________ (医疗的) workers are badly needed in those earthquake-hit areas.
3. I don't think the watch gives you good __________ (价值) for your money.
4. The tourists had no ___________ (选择) but to wait for the next train.
5. How are you going to ___________ (证明) that it is very difficult for giant pandas to survive in the wild?
