Here's a sentence from a textbook
Before I left home, I promised my parents that I would return.
According to the given instruction, I'm suppose to rephrase it into a participial sentence.
One of my answers, however, according to my teacher, is wrong. But she didn't explain to me why. She just told me that before wasn't suppose to be in the middle of the sentence.
Here's the wrong one:
I promised my parents before leaving home that I would return.
Could anyone explain it to me? Thank you!