@article{oai:nagasaki-u.repo.nii.ac.jp:00019948,
 author = {Sonoda, Kenji},
 issue = {2},
 journal = {長崎大学医学部保健学科紀要, Bulletin of Nagasaki University School of Health Sciences},
 month = {Dec},
 note = {In All (What, The first thing) you have to do ..., "have" is semantically linked with the following "to" and it means obligation. However, no explanation seems to have been made so far as to why this is so. This article tries to explain it from two viewpoints. In such structures as What do you have to eat?, at times the verb "have" is semantically connected with "to," while at times it is not, in the latter case of which "have" means "to possess." In OE there were no such VPs as have to: "have" had nothing to do with "to". Have to came to have the meaning of obligation in early ModE., 長崎大学医学部保健学科紀要 = Bulletin of Nagasaki University School of Health Sciences. 2001, 14(2), p.15-18},
 pages = {15--18},
 title = {Obligation and Possession in All you have to do is ... and Its Related Structures},
 volume = {14},
 year = {2001}
}