根据下列句子及所给汉语注释，写出空缺处各单词的正确形式，每空只写一词。

1.This is Johnson's _____ (第二十) birthday.

2. Music is relaxing, and we have music on _____(星期三).

3. They don't like _____(喜剧片).

4. Our class teacher is very _____ (严格的) with us.

5. Some students don't like math, because it's _____(困难的).