14- An offeror may specify in an offer the manner by which the offeree must accept the offer. True Or False 15- An offer is effectively revoked when the offeree or the offeree's agent learns of the revocation presuming that the offer, before that time, has not been accepted. True or false 16- Assuming that the offer does not state how it is to be accepted, acceptance will be effective only at the time the offeror learns of acceptance. True Or False 17- Past consideration is not legally sufficient consideration to support a promise. True Or False 18-Courts are concerned about the legal sufficiency of consideration and rarely are they concerned about its adequacy. True Or False 19- In Hamer v. Sidway, the court ruled that refraining from exercising a legal right does not constitute legally sufficient consideration. True or False 20- The pre-existing legal duty rule prevents a party from claiming that the performance of a legal duty constitutes legally sufficient consideration. True or False