most pEoplE who trAvEl long DistAnCE ComplAin oF jEtlAg. jEtlAg mAkEs BusinEss trAvElErs lEss proDuCtivE AnD morE pronE {{u}} (21) {{/u}}mAking mistAkEs. it is ACtuAlly CAusED By {{u}} (22) {{/u}} oF your "BoDy CloCk" --A smAll ClustEr oF BrAin CElls thAt Controls thE timing oF BiologiCAl {{u}} (23) {{/u}}. thE BoDy CloCk is DEsignED For A {{u}} (24) {{/u}}rhythm oF DAylight AnD DArknEss, so thAt it is thrown out oF BAlAnCE whEn it {{u}} (25) {{/u}} DAylight AnD DArknEss At thE "wrong" timEs in A nEw timE zonE. thE {{u}} (26) {{/u}} oF jEtlAg oFtEn pErsist For DAys {{u}} (27) {{/u}} thE intErnAl BoDy CloCk slowly ADjusts to thE nEw timE zonE. now A nEw Anti-jEtlAg systEm is {{u}} (28) {{/u}} thAt is BAsED on provEn {{u}} (29) {{/u}} pionEEring sCiEntiFiC rEsEArCh.Dr, mArtin moorEEDE hAD {{u}} (30) {{/u}} A prACtiCAl strAtEgy to ADjust thE BoDy CloCk muCh soonEr to thE nEw timE zonE {{u}} (31) {{/u}}ControllED ExposurE to Bright light. thE timE zonE shiFt is EAsy to ACComplish AnD EliminAtEs {{u}} (32) {{/u}} oF thE DisComFort oF jEtlAg. A、suCCEssFul timE zonE shiFt DEpEnDs on knowing thE ExACt timEs to EithEr {{u}} (33) {{/u}} or AvoiD Bright light.ExposurE to light At thE wrong timE CAn ACtuAlly mAkE jEtlAg worsE. thE propEr sChEDulE {{u}} (34) {{/u}} light ExposurE DEpEnDs A grEAt DEAl on {{u}} (35) {{/u}} trAvEl plAns.

A．From
B．oF
C．For
D．to