Student or Learner
May anyone explain this kind of sentence strucure to me?
"Used wisely,a few key points can form an impressive answer."
The sentence is pretty vague. Another way of saying it would be "A few key points that are used wisely can form an impressive answer."
The first two words in your sentence, "Used wisely," form what grammarians call an "absolute clause." Try to find that phrase in a Longman or Cambridge grammar.