问题补充:
The boy is to look after his sister.
A. enough old
B. enough young
C. young enough
D. old enough
答案:
A. enough old
B. enough young
C. young enough
(答案→)D. old enough
解析:enough的意思是足够的,可做形容词和副词,一般放在被修饰词的后面。Old年老的;young年轻的。句意:这个男孩年龄足够大照顾他的妹妹了。故选D。