根据句意及首字母提示补全单词。

1. The m_________ Olympics started in 1896.

2. There are some f_________ students in our class. They come from Canada.

3. We should do more exercise to b_________ up our bodies.

4. Nothing is difficult in your study if you put your h_________ into it.

 5. Jim feels s_________ in class because he went to bed too late last night.