题目

    In the 1920s and 30s the airlines were just beginning. It was unusual for people to travel by air because it was expensive and dangerous. In those days, there were no flight attendants to look after the passengers. Young men ,or “stewards” helped the passengers onto the airplane and carried the passengers’ luggage(行李)but they did not provide food and drinks. But then in 1930,a woman called Ellen Church invented the “stewardess”.     Ellen Church was born in 1904 on a farm in Iowa. She was a different child. She didn’t want to work on a farm or marry a farmer —The story of Tom Sawyer ______ in Missouri, America, in the 19th century. A. had happened                                                     B. was happening C. has happened                                                      D. happened