1. What ____ an excellent player from an average one is that the former learns from his errors, while the latter repeats them.
A. defines B. describes C. differentiates D. discourages
【答案解析】 C
【详解】考查动词辨析。句意：一个优秀的球员和一个普通的球员的区别在于前者从他的错误中学习，而后者则重复它们。A. defines规定；使明确；B. describes描述；C. differentiates区分；区别；D. discourages使气馁。 根据an excellent player from an average one以及下文the former和the latter可推断，此处表示优秀球员和普通球员的区别。故选C。
