高原现象是指什么？
Itwasneverclear_______themanhadn’treportedtheaccidentsooner
TheNativeAmericaninterpreterSacajaweawasavaluablememberoftheLewisanddarkexpeditionin1805.
Thereasonwhyheadaptedtothenewsituationsquicklyisthathehasa_____attitude.
Willallthose_____theproposalraisetheirhands?
