Unlike the steam locomotive, which required an hour or two of firing up before it was possible to move under its own power, nearly full power could be summoned almost instantly from the cold engine of a diesel locomotive.

a.it was possible to move under its own power, nearly full power could be summoned almost instantly from the cold engine of a diesel locomotive.

c.it could move under its own power, the diesel locomotive could summon nearly full power from a cold engine almost instantly

e. moving under its own power, almost instantly a diesel locomotive could summon nearly full power from a cold engine

答案c。我觉得e的迷惑性很大，给出不选E的理由是，before moving这种结构没有表示出could这个含义，还有一个就是almost intantly的位置，作者说在E中这种位置有歧义。我始终对状语的位置理解有偏差，我觉得在这样的一个完整句里，没有从句，没有其他动词，almostly intantly除了修饰谓语动词还能有别的什么歧义呢？如果说状语离修饰成分越近越好，那么应该放在谓语动词的前面或者后面，而看选项C和E，放在句中和句尾又有什么区别呢？我只能理解为放在句首有强调的嫌疑，但我觉得此解释牵强。

所以也就是说从语法结构上E没有什么错，只能说C更好……

He could run even faster.

Even faster he could run.

 He only saw me yesterday.

Only he saw me yesterday.

看出不同了嗎？

 第一个only是副词，作状语。

第二个only是形容词，作表语。

almost instantly如果放在句首，感觉上对前一个句子有承接作用。就是说在前一个动作发生的同时，这一个动作也发生了。I heard a gunshot. Almost instantly I heard a scream from a lady.

还有就是，当看到"was possible"的时候，第一反应就是此题在考情态动词。这种成份在答案中应该保留。