Questions 16-20 are based on the following passage: 　　Ernest Hemingway wrote a short story called "The Capital of the World." In it he tells’ about a Spanish father who wants to reconcile (和解) with his son who has run away to Madrid. In order to locate the boy he takes out this ad in the newspaper: "Paco, meet me at Hotel Montana at noon on Tuesday. All is forgiven. Love, Papa." 　　Paco is a common name in Spain, and when the father goes to the square he finds 800 young men named Paco waiting for their fathers. 　　What drew them to the hotel As Hemingway tells it, it was the words "All is forgiven." The father did not say, "All WILL BE forgiven IF you do this or that." Not, "All WILL BE forgiven WHEN you do such and such." He simply says, "All is forgiven." No strings attached. 　　And that’s the hard part—un—attaching the strings. The origin of the expression "no strings attached" may go back to ancient times when documents were written on parchment (羊皮卷) that were rolled up and secured with a string. 　　The Babylonian Talmud (犹太法典) tells of a man who gives his wife a bill of divorce on such a parchment, but holds onto the string so that he can snatch it back, should he choose to do so. The divorce, therefore, is not considered valid since he will not give it freely. Similarly, love, forgiveness or friendship that is given with strings attached are not valid, since they can be snatched back at any time. It can be learned from the last paragraph that ____________.