悲观: pessimistic...
山脉: mountain range...
短暂: of short duration, brief, momentary...
回归: to return to, to retreat, regression (statistics)...
牙膏: toothpaste...
飞行员: pilot, aviator...
地势: terrain, topography relief...
考察: to inspect, to observe and study, on-the-spot investigation...
攻克: to capture, to take, to overcome, to solve...
推选: to elect, to choose, to nominate...
