科学家们正在研究反重力装置，以使未来车辆能够悬浮在空中。

Scientists are studying ___antigravity devices to make future vehicles float in mid-air.

他的乐观态度像反重力装置一样，总能在团队低落时提升大家的情绪。

His optimism works like ___antigravity, always lifting the team's mood when they're feeling down.