問題:George offered by letter to sell his car to Clare for ?5,000, and asked her to reply by post.The letter was posted on 7 July. Having heard nothing, George decided to withdraw his offer and sent a letter to that effect on 14 July. Clare only received the offer letter on 17 July and immediately telephoned her acceptance to George's wife. She confirmed this by letter posted on 17 July. She received George's letter of revocation on 20 July, and on enquiry found that he had sold the car to Amanda.
  What are the consequences of this series of events?
  A. A contract between George and Clare was formed on 17 July, but it has been discharged by George's breach.
  B. The ten day delay from 7 to 17 July is unacceptable and means that the offer has lapsed.
  C. Clare's failure to accept the offer before George's revocation of offer on 14 July means that the offer lapsed and no contract was formed.
  D. A contract was formed by Clare's acceptance on 17 July but George's revocation means that the contract is discharged by agreement.
  答案:The correct answer is: A contract between George and Clare was formed on 17 July, but it has been discharged by George's breach.
  解析George's sale of the car to Amanda is in breach of his contract to sell the car to Clare. That contract was formed on 17 July when Clare posted her letter to George, as acceptance is effective on posting. George's revocation of the offer is ineffective, as a revocation is only effective when it is received by the offeree.