Essential app for GnB students! GnB Listen Up Listening is a must for language study. Put all the audio CDs in my manual into the phone. When you go to school, from bus to subway ... If you listen infinitely, your ears are pierced. GnB teachers' essential app! GnB Listen Up Do not waste time looking for audio CDs for classes. Put audio CDs of all lessons into your phone. Sound quality is better when you connect your smartphone to external speakers. (Bluetooth, wired, etc.) ■ App recommendation