•  adapt (adjust to); adept (skilled); adopt (take as one's own) 
     •  advice (guidance); advise (to give guidance) 
     •  aerie (nest); airy (breezy); eerie (spooky) 
     •  aid (help); aide (assistant) 
     •  aisle (passage); isle (island); I'll (you're really in the wrong field if you confuse this one)
     •  alley (passageway); ally (friend) 
     •  all ready (prepared); already (previously) 
     •  allusion (indirect reference); illusion (misperception) 
     •  Apparent usually means obvious; avoid using it to mean likely or probably, as in apparent heart attack.  (See doubtful.) 
     •  appraise (to set a value on); apprise (to inform) 
     •  arc (curve); ark (boat) 
     •  ascent (upward slope); assent (agreement) 
     •  assay (to analyze); essay (to attempt) 
     •  bring (carry toward); take (carry away) 
     •  auger (a tool); augur (to predict) 
     •  bail (money; to empty); bale (bundle) 
     •  breach (violation); breech (buttocks) 
     •  bazaar (marketplace); bizarre (weird) 
     •  bloc (coalition or common group); block (all other meanings) 
     •  born (came to life); borne (carried) 
     •  borough (town); burro (donkey); burrow (hole) 
     •  bouillon (soup); bullion (metal) 
     •  braise (to cook); braze (to solder) 
     •  broach (to begin); brooch (pin) 
     •  cannon (gun); canon (law) 
     •  caster (wheel); castor (oil) 
     •  censor (examiner); censer (vessel); censure (blame)