Unlike in other transportation industries, there are no minimum standards set by government or industry for qualifying for being an engineer on a train. (A) Unlike in other transportation industries, there are no minimum standards set by government or industry for qualifying for being (B) Unlike other transportation industries that have minimum standards set by government or industry, there are none for qualifying to be (C) Although the government or industry usually sets minimum standards for transportation industries, no such one has been set for qualifying as to being (D) Although the government or industry usually sets minimum standards for transportation industries, no such standard has been set for qualifying to be（D） (E) Although there are usually minimum standards set by government or industry for transportation industries, there is none for qualifying and being 好像没有人问过。答案选D没有问题。我的问题是D选项中的qalifying to be an engineer on a train, qualify to be 是什么意思呢？好像qualify 只for & as? 请不吝指教！先谢谢了。 | 
