As International Olympic Committee inspectors on Monday launch their last inspection of Greece’s venues before the August Games, the largest question mark looming over Greece’s frenzied preparations is expected to dissolve into a clear answer. After two weeks of preparations, Athens 2004 organizers are under strong pressure to start sliding into position the 18,000-ton steel-and-plastic roof designed for the main Olympic stadium by Spanish architect Santiago Calatrava. «We hope that when we arrive the roof will have made some sign of movement on Monday,» Gilbert Felli, the IOC’s executive director of the Olympics, told The Associated Press yesterday. «If for some reason… the roof has not started to move, of course we have discussion.» The IOC has repeatedly voiced fears that delays with the roof could hold back other crucial work at the stadium. The 80-meter-high structure is planned to slide in two halves, which must cover distances of 71 and 64 meters. Greek sources said the operation could start any time during the next two days.