II.off [美 ɔf, ɑf, 英 ɒf]副off often appears as the second element of certain verb structures in English (break off, pay off, take off, etc). For translations, see the relevant verb entry (break, pay, take, etc).
I.on [美 ɑn, ɔn, 英 ɒn]介词on often appears as the second element of certain verb structures in English (count on, lay on, sign on, etc). For translations, see the relevant verb entry (count, lay, sign, etc).
This will allow for vertical take-off and landing capabilities, hovering on the spot, and more energy-efficient operation than traditional propellor-based systems.