Tense

Please check out the following sentences. Is the tense in each blank acceptable?

(1) No sooner had I left school than it began to rain.

(2) As soon as you finish your work, I'd like to talk to you for a few minutes.

(3) For thousands of years, people have known that no two people ahve the same fingerprints.

(4) The patient had waited in the emergency room for almost two hours before the doctor finally came.

(5) I'm sorry. He is not here. He has gone to Japan.

(6) If he sold the stone, he thought, he would have enough money for the rest of his life.