be afraid of/to的问题用法
我有一道英语题不太明白!`
the little girl is afraid ___the darkness and she is afraid __alone.
A.of,of sleeping
B.to,to sleep
C.of,to sleep
D.to,of sleeping
A/C
我就不明白为什么前面那一空必须要用be afraid of,而不能用be afraid to,而后面两个都行?