Sentence Correction

mundasingh123 wrote:But Ron , the formal text books on SC dont deal with structure issues apart from some points such as...

see, this is my exact point: you're depending only on what you learn in the formal textbooks, rather than trying to synthesize what you see elsewhere in the writing of native english speakers.
this isn't how you get good at a language! you don't just concentrate *only* on the points that are given to you formally in grammar books and the like; those are a great way to learn very specific finer points of the language, but you can't get an overall "feel" for the language that way. to understand how the language truly flows, you should also check out the writing of well-educated native speakers.

this is what i'm talking about: by the time someone has posted 1000 times, they have probably seen at least a hundred questions from native speakers. (e.g., a moderator writes "What do you think is wrong?" and not "What you think is wrong?")
therefore, if someone has 1000 posts and is still writing "Why A is wrong?", then they must have ignored the moderators' writing style over a hundred times in a row!

this is the deal: when textbooks explain how super-specific finer points of the language work, they are assuming that you already have a decent command of the basic flow of the language. if you don't, then your task is to pay attention not only to the fine specifics, but also to the backbone structures that you see in educated native speakers' writing.

sachindia wrote: How can inventory turn itself? Doesn't it have to be turned through some efforts by somebody?

this is a good question; unfortunately, the answer is basically just "that's how the expression is used". when inventory is sold, one says that it turns over.
most importantly, though, note that this difference is irrelevant to the solution of the problem, as choice (d) contains a fundamental construction that simply doesn't exist in the language.

in general, you should avoid using active/passive differences unless you actually NEED to them to solve the problem.
in other words, unless an active/passive difference is the ONLY distinction between two answer choices, you should ignore it and use the other elements of the problem to solve it.
the reason is basically what you've seen here: many active/passive differences depend primarily on idiomatic usage that can't be figured out logically. (this isn't just true for relatively obscure expressions like inventory turnover; it's also true for some very common constructions. for example, it's acceptable to write that the event ended at 7 p.m., even though, logically speaking, someone had to take some action to end the event.)

if, perchance, you do encounter a problem on which an active/passive difference is essential, it should be pretty easy to tell which voice makes sense and which doesn't.