Заполните пропуски соответствующими словами в нужной форме.

In southern England on the Salisbury Plain stands a circular ___ (FORM) of rocks called Stonehenge. People from around the world ___ (IMMEDIATE) recognize pictures of Stonehenge, as it's one of the world's most famous ___ (ARCHEOLOGY) sites. It's also one famous of Earth's greatest mysteries. What is Stonehenge? Who built it? Why was it built? These questions remain ___ (ANSWER) today, some 4,600 years after Stonehenge was built by prehistoric people who left no written records. There is no shortage of theories about Stonehenge, though. Ancient folklore holds that Stonehenge was created by King Arthur's wizard, Merlin, out of ___ (MASS) stones from Ireland that had been built there by giants. Others believe the stones were erected thousands of years ago by ___ (INVADE) from Denmark.