互补: complementary, to complement each other...
水面: water surface...
收到: to receive...
危及: to endanger, to jeopardize, a danger (to life, national security etc)...
对外: external, foreign, pertaining to external or foreign (affairs)...
咽喉: throat...
面积: area (of a floor, piece of land etc), surface area, tract of land...
激活: to activate...
幕后: behind the scenes...
极度: extremely...