13. After getting a transmition from Alyx's father, Gordon and her try to find a way into the Citadel. Facing a gorge, both people are unsure as for what to do. In the end, Dog is the one who finds a way. What is it?
From Quiz Half Life 2: Episode One
Answer:
Throw both Alyx and Gordon over in a broken down van.
After Gordon thought of nothing, he is silent after all, Alyx suggests that Gordon somehow use the Gravity Gun to get them across. Dog shows up and disappears. Alyx, worried by that, then realizes what Dog was doing so she told Gordon to get out of the way of the trashed van. Dog wanted both of them to get inside, and he'd throw them across. After clearing the canyon, both of them were in the Citadel. The building, already unstable after the core's current state, couldn't support the weight of the vehicle, so Gordon and Alyx took a 'rollercoaster-esque' ride through the tunnels and corridors of the Citadel before finally landing in a convenient location, unscathed.