quEstions 17--20 ArE BAsED on thE Following pAssAgE. you now hAvE 20 sEConDs to rEAD quEstions 17--20. why Air must BE pumpED into thE plAnEA．BECAusE without Air thE plAnE CAn’t Fly.
B、BECAusE thE plAnE nEEDs Air For its FuEl.
C．BECAusE thE pAssEngErs’ livEs DEpEnD on Air.
D．BECAusE thE pAssEngErs hAvE pAiD For it.