obligation / need / possibility

obligation : 義務

  • [形]liable : 法的な義務の意味も含む
    You will be liable for any damage when you rent a car
  • [形]obliged
    The company is obliged to give a refund if the tour is cancelled
  • [形]forced : 強制(make的な使い方)
    The bank robbers forced him at gunpoint to open the safe.
  • have no choice/alternative but : するしかない
    We had no choice/alternative but to sell our house.
  • [形]mandatory : 必須の(法律、ルール、約束などによって強制される性質のもの,免れないみたいな?)
    The death sentence is mandatory for drug-smuggling in some countries.
  • [形]compulsory / obligatory : 強制
    Was sport compulsory/obligatory at your school?

Need : 必要

  • in need of : ~を必要として(needs/wantsよりフォーマルな言い方)
    This plant is in need of water.
  • need for : 〜を必要とする (we feel a need)
    There’s need for more discussion on the matter.
  • an absolute necessity : 必ず必要
    A car is an absolute necessity if you live in the countryside and there is no public transport.
  • requirements : 必要条件
    What are the requirements for a Master’s course in English?

possibilities : 可能性

  • Is there any chance/possibility you’ll be free next week?
  • [形]inevitable : 必然
    A rise in oil prices is inevitable as oil supplies run out across the world.
  • It is doubtful whether : かどうかは怪しい
    It is doubtful whether the economy will improve next year.
  • It is probable that : たぶん〜だろう
    It is probable that the next government will change the tax laws.
  • certainty : 確実
    Most scientists believe that climate change is no longer just a possibility but is now an absolute certainty.