搜索智能精选题目 WGS-84地心椭球基本元素为( )A. a=6378245m,f=1:298.3 B. a=6378140m,f=1:298.257 C. a=6378338m,f=1:297.0 D. a=6378137m,f=1:298.257223563答案 D