He was educated at a local grammar school, _____ he went on to Cambridge. [ ]

A. from which

B. after that

C. after which

D. from this

原子可以用三个量表示，即，其中A减Z指的是（）

A、原子序数

B、原子质量序数

C、和外电子数

D、核内质子数

E、核内中子数