Why don’t you stay here for a few more minutes? _________, and my parents will be worried. A. It’s getting late B. All right C. It’s OK. D. I hope so. 答案:A“歼20”是我国自主研制的新一代隐身重型歼击机,具有卓越的机动性能,当它在空中加速向下俯冲时,动能____________,重力势能_____________。(选填“增大”、“不变”或“减小”)