"I could have been a great doctor if I had had enough money to pay for medical school."
"He could not have been there" is the correct sentence. It conveys the idea that he was unable to have been at the specified place.
Example sentence - If they would have been considerate of their hosts and not self-invited, accommodations could have been plentifully dispersed.
yes. I have been to a reef.
Sure: "I mourn the loss of what could have been."
"You could have been a doctor" is correct. This sentence implies that becoming a doctor was a possibility in the past. "You should have been a doctor" implies that becoming a doctor was the correct choice in the past.
The flood's effect could have been delayed by this overflow basin.
That can not be said in a sentence.
A good sentence could be: Does she have her hair colored? Yes, she has had a dye job. I have to go to the store, she has not been there yet.
While Kathy's fall was painful, it could have been worse.
Yes, had and had are correct. You could drop the first 'hand' and still have a good sentence. BUT who is "They"? and who is "her"? That makes the sentence confusing. You could change it to: Cathy's parents had just arrived, but her husband had been staying nearby for a while.
We listed every state we've been to for our homework assignment
my mother always have been a sparing woman