MynameisWangKun.EversincemiddleschoolmysisterWangWeiandIhavedreamedabouttakingagreatbiketrip.Twoyearsagosheboughtanexpensivemountainbikeandthenshepersuadedmetobuyone.LastyearshevisitedourcousinsDaoWeiandYuHangattheircollegeinKunming.TheyareDai(傣族人)andgrewupinwesternYunnanProvinceneartheLancangRivertheChinesepartoftheriverthatiscalledtheMekongRiverinothercountries.WangWeisoongottheminterestedinbikeridingtoo.Aftergraduatingfromcollegewefinallygotthechancetotakeabiketrip.Iaskedmysister"Wherearewegoing?"ItwasmysisterwhofirsthadtheideatoridealongthewholeMekongRiverfromwhereitbeginstowhereitends.Nowsheisplanningourscheduleforthetrip.

Mysisterhasoneseriousshortcoming(缺点).Shecanbereallystubborn(固执的).Althoughshedidn'tknowthebestwayofgettingtoplacessheinsisted(坚持)thatsheorganizethetripproperly.NowIknowthattheproperwayisalwaysherway.Ikeptaskingher"Whenareweleavingandwhenarewecomingback?"Iaskedherwhethershehadlookedatamapyet.Ofcourseshehadn't;mysisterdoesn'tcareaboutdetails(细节).SoItoldherthatthesource(源头)oftheMekongRiverisinQinghaiProvince.Shegavemeadeterminedlook—thekindthatsaidshewouldnotchangehermind.WhenItoldherthatourjourneywouldbeginatanaltitudeofmorethan5000metressheseemedtobeexcitedaboutit.WhenItoldhertheairwouldbehardtobreathe(呼吸)anditwouldbeverycoldshesaiditwouldbeaninterestingexperience.Iknowmysisterwell.Onceshehasmadeuphermindnothingcanchangeit.FinallyIhadtogivein.

SeveralmonthsbeforeourtripWangWeiandIwenttothelibrary.Wefoundalargeatlaswithgoodmapsthatshoweddetailsofworldgeography.FromitwecouldseethattheMekongRiverbeginsinaglacieronamountaininQinghaiProvince.Atfirsttheriverissmallandthewaterisclearandcold.Thenitbeginstomovequickly.ItbecomesrapidsasitpassesthroughdeepvalleystravellingacrosswesternYunnanProvince.Sometimestheriverbecomesawaterfall.WewerebothsurprisedtolearnthathalfoftheriverisinChina.AfteritleavesChinatheMekongbecomeswidebrownandwarm.AsitentersSoutheastAsiaitspaceslows.AtlasttheriverdeltaenterstheSouthChinaS