Question

The unforgettable ball was the last happy moment ________ I enjoy myself．

1. A.
   when
2. B.
   that
3. C.
   which
4. D.
   where

Answer 1

A
I enjoy myself我玩得高兴，空格处缺少状语，因此排除B、C项。根据句意先行词moment在定语从句中作时间状语，故选择A项。