When mom said, " The C-A-N-D-Y is hidden on the top shelf, " I knew where the candy was.

当我的母亲说，“C-A-N-D-Y 藏在架子顶层，” 我就知道糖在哪里。

The did he changes to d y d y?

他改成d y d y了吗？

Putting this together, you get a vector A-X plus B-Y-C-X plus D-Y.

把这些放在一起 就得到向量a-x+B-Y-C-X+D-Y。