已知平行四边形ABCD两条对角线的交点坐标是坐标系的原点，点A，B的坐标分别为（-1，-5），（-1，2），则C，D的坐标分别是______，______．

We are going to discuss the way of reading works ____ it is used for real life purposes, and this should give you a better understanding of it.

A．that

B．which

C．where

D．when