it wAsClArk’s First visit to lonDon: unDErgrounD rAilwAy.AgAinst (36) ADviCE oF his FriEnDs, hE DECiDED to go thErE AFtEr 5 o’CloCk in thE AFtErnoon. this is A BAD timE to (37) in lonDon, BECAusE numErous pEoplE go homE From work (38) this hour. hE hAD to join A long (39) oF pEoplE who wErE wAiting For tiCkEts. whEn his turn CAmE, hE hAD somE DiFFiCulty in mAking himsElF (40) By thE mAn sElling tiCkEts. howEvEr, hE got thE right tiCkEt (41) thE EnD AnD, By Asking pEoplE thE (42) , hE Also FounD thE right plAtForm. it wAs pACkED Fight (43) pEoplE. hE DiD not (44) to gEt on thE First trAin, But hE wAs (45) to movE nEArEr to thE EDgE oF thE plAtForm so As to BE in A BEttEr (46) to gEt on thE nExt onE.
whEn this trAin CAmE in,ClArk wAs (47) ForwArD on to thE trAin By thE (48) oF pEoplE From BEhinD、thE Doors ClosED AnD thE trAin (49) oFF. hE wAs unABlE to sEE thE nAmEs oF thE stAtions whErE thE trAin stoppED, But hE knEw thAt thE stAtion hE wAntED wAs thE sixth (50) Along thE linE. whEn thE trAin got to thE sixth stAtion,ClArk got oFF, FEEling gooD thAt his (51) hAD BEEn so EAsy.But hE suDDEnly (52) thAt hE hAD ComE to A stAtion hE hAD nEvEr hEArD oF. hE ExplAinED his DiFFiCulty to A mAn who wAs stAnDing on thE plAtForm, with A (53) on his FACE, thE mAn (54) ClArk thAt hE hAD CAught A trAin going in thE oppositE (55) .
A、unDErstAnD
B．unDErstooD
C．unDErstAnDing
D．unDErstAnDABlE