No one had SEEN / SEEING inside the tomb for 3000 years.
seen
I HAD BEEN THINKING / HAD THOUGHT about you when the phone rang.
I had been thinking
HAD THEY INTERVIEWED / HAD THEY BEEN INTERVIEWING the archeologist before?
Had they interviewed
It was obvious he'd failed the exam. He HADN'T EVEN OPENED / HADN'T EVEN BEEN OPENING his text book.
hadn't even opened
Had Schliemann LOOKED / BEEN LOOKING for Troy a long time when he found it?
been looking
