①By the 1920s，he had become an explorer，searching for the tombs of the Egyptian kings.
②I returned the book that I had borrowed.
③Upon their entering the tomb，Cater's lucky pet bird，which he had left in Cairo，was swallowed by a snake.
④Then，a few months after Carter had opened the tomb，Lord Carnarvon，who was also present when the tomb was opened，fell ill with a fever and died in Egypt.
⑤He said he had worked in that factory since 1949.
⑥I had been at school for half an hour when Li Lei came.
