在中枢神经系统内，神经纤维聚积而成的结构为（）
A.白质
B.灰质
C.髓质
D.神经核
E.神经节
参考答案：A
He took _______ look at my bike and asked me to buy _______ new _______. [ ]
A. a...a...one
B. the...a...one
C. a...the...one
D. the...the...one
