圆明园又称为圆明三园，因为它是由（ ）构成的。
The Yuan-Ming Yuan Imperial Garden is called three gardens of the Yuan-Ming Yuan Imperial Garden, because it's consisted by()

A．圆明园
Yuan-Ming Yuan Imperial Garden
B．畅春园
Garden of Everlasting Spring
C．长春园
Chang-Chun Yuan
D．万春园
Wan-Chun Yuan