题干
―I'm considering returning home. I just can't get used to the food here.
―Take it easy. _______.
A：Storms make trees take deeper roots.
B：East or west, home is best.
C：From small beginning come great things.
D：All things are difficult before they are easy.
答案(点此获取答案解析）
D
和
的图象的对称中心完全相同，若
，则
的取值范围是 （ ）