[求助]GWD17-Q20:

20 GWD17-Q20:

Construction of the Roman Colosseum, which was officially known as the Flavian Amphitheater, began in A.D. 69, during the reign of Vespasian, was completed a decade later, during the reign of Titus, who opened the Colosseum with a one-hundred-day cycle of religious pageants, gladiatorial games, and spectacles.

A.      which was officially known as the Flavian Amphitheater, began in A.D. 69, during the reign of Vespasian,

B.       officially known as the Flavian Amphitheater, begun in A.D. 69, during the reign of Vespasian, and

C.      which was officially known as the Flavian Amphitheater, began in A.D. 69, during the reign of Vespasian, and

D.      officially known as the Flavian Amphitheater and begun in A.D. 69, during the reign of Vespasian it

E.       officially known as the Flavian Amphitheater, which was begun in A.D. 69, during the reign of Vespasian, and

正确答案是c，但是我不明白，不是说主动和被动是不能够平行放在一起的么？为什么在这句里面，began可以和was completed放在一起？