If you already own the physical CD but have no CD drive, you can legally rip it to MP3 for personal use using software like iTunes, VLC, or Exact Audio Copy. Search for: “Minna no Nihongo Choukai Tasuku 25” + “CD” on Amazon Japan Or visit the 3A Corporation website to check for digital audio availability. For free practice, use YouTube N4 listening exercises focused on conditional forms (と・ば・たら・なら).