---Will you walk a little faster?　 ---I was afraid you could not .A. walk upB. go upC. ke

问题补充：

---Will you walk a little faster?

---I was afraid you could not .

A. walk up

B. go up

C. keep up

D. catch up

答案：

A. walk up

B. go up

(答案→)C. keep up

D. catch up

解析：短语辨析。 A. 走上；等着 B. 增长；上升 C.保持；继续；不落后 D. 赶上。句意：你能走的快一点吗？——我恐怕你跟不上。catch up强调开始是落后的，从后面追上。keep up强调始终保持跟在后面，不掉队。结合语境可知选C。