题目内容：

Dont worry .I'm sure i can run _____ to catch up with them.
a.slowly enough
b.enough up with them
c.fast enough

优质解答

别担心,我相信我能跑得足够快追上他们.
A 足够慢(慢了还怎么追得上)
B 这么表述是错误的.有了with them 后面还有catch up with them?而且虽然有了“足够”,但是足够怎么着?足够慢?显然不行,句子意思不全.
所以选C 足够快