#!/usr/bin/awk -f 

function reset() {
  cond = 0
  reb = ""
}
function output() {
  print reb
}

$0 == "<entry>" {
  reset()
}
$0 == "</entry>" {
  if (cond)
    output()
}
$0 == "<pos>&v1;</pos>" {
  cond = 1
}
/<reb>/ {
  reb = $0
}