A.絕對(duì)高程之差與相對(duì)高程之差之和為零 B.絕對(duì)高程之差與相對(duì)高程之差的大小不確定 C.絕對(duì)高程之差比相對(duì)高程之差要大 D.絕對(duì)高程之差與相對(duì)高程之差一樣大