I often hear her _____this song. Listen! Can’t you hear her ____in the next room?
A:sing, sing
B:singing, singing
C:singing, sing
D:sing, singing
①建立在性恶论基础上 ②认为君臣之间无信任可言
③为君主专制出谋划策 ④成为君权神授的思想来源
对于函数y=f(x),如果存在区间m,n,同时满足下列条件:①f(x)在m,n内是单调的;②当定义域是m,n时,f(x)的值域也是m,n,则称m,n是该函数的“梦想区间”.若函数f(x)=a+1a-1x(a>0)存在“梦想区间”,则a的取值范围是( )