4 In terms of physics, the characteristic feature of the roller coaster is that the cars' potential energy, gained through their being lifted by a chain drive through the Earth's gravity to the top of the first drop, has been converted to kinetic energy by the time the ride ends.
(A) cars' potential energy, gained through their being lifted by a chain drive
(B) cars' potential energy, a gain achieved as they are lifted by a chain drive
(C) potential energy from the cars' being lifted by a chain drive
(D) potential energy of the cars, gained as a chain drive lifts them
(E) potential energy gained by the cars, being achieved while a chain drive lifts them

正确答案是D，请问大家各个选项如何找出错误进行判断呢？谢谢fficeffice" /> [em13]

A、B cars' potential energy这样的表达不如potential energy of the cars，同时使后面的their、they没有指代对象
C from the cars' being lifted by a chain drive 错
E being achieved 错 gained、 achieved意思重复

不知道这样理解对不对fficeffice" />