Last night on the news I heard the newsreader (not really a reporter, alas) say something like “After sitting in her car for four hours at subfreezing temperatures, police officers were able to rescue the woman.” You may wonder why the police were sitting in the woman’s car for hours and why they waited so long to rescue her.
The answer is, of course, that it was the woman, not the police, who sat in the car for hours. This is the only thing that makes sense in the context. But from a grammatical perspective, the initial clause, lacking a subject of its own, is presumed to refer to the subject that immediately follows. You might think this is picky since, after all, the meaning is clear. But that’s not always so. That’s why it’s important to put the modifying clause immediately before or after the thing it modifies.
Take this example: “After winning the match, I asked Joe to buy me a beer.” Who won the match? It makes sense either way. Maybe we had a friendly bet and he owed me the beer since I won. Or maybe he won and I was hoping he’d buy me a beer as gracious consolation prize. The logic applies even if I was the one buying the beer for him. But what did your brain tell you when you read the sentence? You assumed I had won the match. Why? Because you intrinsically know the rule that the thing immediately following the clause is the thing referred to. Of course the best phrasing, at least for purposes of clarity, is to include the subject of the clause in the clause, e.g., “After she had sat in the car for four hours, the police rescued the woman.” The newsreader made three of these misplaced clause errors in a row in that newscast.