"Diamond cut diamond" is an idiom, which reflects（ ）.
A、the constituents of idioms can't be replaced
B、the word order can't be inverted
C、the constituents of an idiom can't be deleted
D、many idioms are grammatically unanalysable
【正确答案】：D
【题目解析】：虽然这句习语“棋逢对手”从语法上分析是不正确的，但我们依然这样在用，说明了习语的一个特点就是不讲究语法。
