what's the difference between these:
1. I had a headache
2. I have been having a headache
3. I have had a headache
4. I had been having headache
5. I had had a headache
6. I'm having a headache
7. I have a headache
correct me if I'm wrong. here are my assumptions:
1. number one implies that I no longer have a headache.
2. number two implies that I'm still having a headache from previously, so what's the difference with number 6 and 7?
I don't really understand the other. thanks