Понимание структурно-смысловых связей в тексте

The pyramid is thought to have been built A ______. It is the last of the seven wonders of the ancient world still standing. It contains three main chambers: the Queen’s Chamber, the Grand Gallery and the King’s Chamber, B______. Strangely, though, there are two tunnels, about 20 centimetres by 20 centimetres, that extend from the north and south walls of the Queen’s Chamber and stop at stone doors C______.

The function of these tunnels and doors is unknown, but some believe that one or both could lead to a secret chamber. Several attempts have been made to explore the tunnels using robots. In 1993, a robot crawled some 63 metres up the tunnel in the south wall and discovered D______. Metal is not part of any other known structure in the pyramid, and the discovery ignited speculation that the pins were door handles, keys or even parts of a power supply constructed by aliens.

Now a robot designed by engineer Rob Richardson from the University of Leeds, UK, has crawled up the tunnel carrying a bendy ‘micro snake’ camera that can see around corners.

As the camera can see around corners, the back of the stone door has been observed for the first time, scotching the more fanciful theories about the metal pins. The pictures from behind the pins show that they end in small, beautifully made loops, indicating that they were more likely ornamental rather than electrical connections. Also, the back of the ‘door’ is polished so it must have been important. It doesn’t look like it was a rough piece of stone used to stop debris getting into the shaft.

Images sent back by the camera have revealed hieroglyphs written in red paint and lines in the stone that could be marks left by stone masons E ______. ‘If these hieroglyphs could be deciphered, they could help Egyptologists work out F ______’ says Richardson.

1. why these mysterious shafts were built
2. as a tomb for the pharaoh Khufu
3. when the chamber was being carved
4. before they reach the outside of the pyramid
5. that their function is symbolic
6. what appeared to be a small stone door set with metal pins
7. which has two air shafts connecting it with the outside world