Tell me one of: Q, T, S, S150, S135, S120, or woman only. T is the Part 4 lecturer, whose pitch is in a woman's range.
Whole story, Part 3 man, sample Q (108 seconds)
Spots the machine flagged. Tap to hear each one from a little earlier:
It was economical, she explained, because the water was recycled inside a transparent tank.
When a visitor squeezed a rubber bulb, a small buoyant diver would slowly submerge, then drift back to the surface.
One team gave an overly long presentation about aircraft cabins, and the judges, clearly unimpressed, began to fold their programmes and check their watches.