Travelingcanbefunandeasy.Avacationtr iptoanothercountr yisespeciallyenjoyablewhenthetr avelingconditionsaregood.Goodtr avelingconditions(11)acomfortable modeoftr ansportation，knowledgeofthecountr y'slanguage，familiarity(12)thecustomsandhabitsofthepeopleinthecountr y，andpleasanttr avelingcompanions.AllofUShavehadnicetr ips(13)this.
Mostofushavealsohadtr ipsthatwewould(14)toforget.ManyconditionsCanproduceabadtr avelingexperience.Forexample，ifthefourconditionslistedabovedonotexist，wewillprobablyhaveabadexperience，(15)atbestadifficult(16).Studentswhotr aveltoaforeigncountr ytostudyoftenhaveadifficulttr ip.Theyusuallytr avelalone.Theydon'tknowthelanguageofthenewcountr y(17).Theyoftenarriveinthenewcountr y(18)ahugeinternationalairport.Fromtheairport，theyneedtofindtheirwaytotheirschool.Maybetheyneedtochangeairplanes，totakeabus，atr ain，orataxi.Theyneedtodoallthisinacountr y(19)everythingisunfamiliar.Later，aftertheexperiencesareover，theyCanlaugh.Butatthe(20)，theyfeelterrible.
A.include
B.conclude
C.hold
D.contain
正确答案：A[解析]包含，包括。
