It is dangerous to allow the children who are swimming in the river.A. enough old to goB.

问题补充：

It is dangerous to allow the children who are swimming in the river.

A. enough old to go

B. not old enough to go

C. not enough old to go

D. not old enough going

答案：

A. enough old to go

(答案→)B. not old enough to go

C. not enough old to go

D. not old enough going

解析：考查enough的位置。首先否定词not应跟在be动词后面，故排除A；enough修饰形容词应放在形容词的后面，故排除C；enough to足够…以至于…，不定式做结果状语。故选B。