“万山不许一溪奔，拦得溪声日夜暄；到得前头山脚尽，堂堂溪水出前林。”这首诗蕴涵的哲理是 [ ]

①事物发展是前进性和曲折性的统一

②新事物必然战胜旧事物

③主要矛盾决定事物的性质和发展方向

④任何事物的存在与发展都是绝对运动与相对静止的统一

A．①②④

B．①②③④

C．①④

D．①

The large size and roughly circular shape of the Pacific made some scientists think that it （） a hole left when the moon separated from the earth.

A. used to be

B. would have been

C. might have been

D. should have been