Re: Plural or Singular After 'Their'?
I never had a phrase for that before: distributive plurals. Thanks for that.
The truth is, Al, natives will use this almost interchangeably and certainly inconsistently.
In most cases, it doesn't matter.
Each dog has one head. Each dog has one leash. Whether you say head/leash or heads/leashes, it won't matter.
Problems arise when it's possible you meant that each person (or dog) had only one of something, but the real-world situation is that they could have several, or at least two.
The girls raised their hands -- probably one hand, like a student answering a question, but maybe both, like people hoping to catch something desirable being thrown to the crowd. Context may tell you which.
And even then, in most cases, it doesn't matter. If what happened next, while the girls stood with their hands in the air, was that a 4-meter, fire-breathing dragon ripped off the roof, ate the wedding cake and the groom, and swatted the band off the dias with his tail, does it really matter if they had one hand up or two?
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.