It seems that the mystery of why the Pyramids were built may (1. have solved?have been solved). Until quite recently people got used (2. to think?to thinking) that they were just tombs for pharaohs. Instead, the connection with astronomy (3.seem ? seems) much more important. Egyptologists have often asked (4. them ? themselves) how long it (5. spent ? took) to build them and why people built them in (6. first place  ? the first place). Experts came up with a suggestion that the Egyptians may have (7. believed in? believed that) the River Nile was the earthly equivalent of the Milky Way. Many agree that the sizes of the three Giza Pyramids are in propotion to the three stars of Orion. Nothing, then, was (8. by the chance ? by chance). Rather, the souls of dead pharaohs were deliberatedly being (9. project ? projected) through shafts to (10. reach at ? reach) their goal of the Orion constellation.