一道简单的英语题Most have been lost on fiying up or landing because

问题补充：根据上面一段话选答案= =。三个不同的答案。Most have been lost on （fiying up or landing）because those are the most difficult times of any flights。those 指括号里面的。A起飞B。flying up and arriving——飞起和到达。这个是答案。C。entering the orbit and landing ——进入轨道和到达,前面部分不对。D。leaving the earth and entering the orbit——离开地面和进入轨道,后面部分不对。知识在于点滴积累,更在于不懈努力。——另外,正在冲采纳率,请记得采用,