When I saw him, I felt happy
When seeing him, I felt happy
When I'm unhappy, I don’t feel like talking
When unhappy, I don’t feel like talking
When I have money, I will buy a new watch
When having money, I will buy a new watch
While I was in Beijing, I had a good time
While in Beijing, I had a good time
If I'm tired, I’m going to take a rest
If tired, I’m going to take a rest
If I have car, I’m taking a road trip
If having car, I’m taking a road trip
Are these correct?