根据下列句子所给汉语意思，写出空缺处各单词的正确形式。
1. _______(事实上), on second thought, I don't think I want to go out tonight.
2. He caught a cold yesterday and ______(遭受) from a headache last night.
3. He was too ________(顽固的) to admit that he was wrong.
4. It is surprising that he can speak _______(流利的) English after such a short time in England.
5. Mr. Wang went back to work after he fully ________(恢复) from the operation.
