—Twice a year.
A:How much
B:How often
C:How long
D:What
若函数f(x),g(x)分别是R上的奇函数、偶函数且满足f(x)+g(x)=ex,其中e是自然对数的底数,则有 ( )
我国最大,也是最长的内流河是( )