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).
For storage, the bottom tiers of the hay bales are sometimes stacked by a machine called a harrowbed, and the hay bucks brought in to top off the stack.
Switching to a stage with different fuels requires the addition of extra support articles; switching to cryogens requires that such support articles top off the stage periodically.