一道简单的英语题
Mosthavebeenlostonfiyinguporlandingbecausethosearethemostdifficulttimesofanyflights.
Themostdifficulttimesofaflightare_________________
A.takingoff
B.flyingupandarriving
C.enteringtheorbitandlanding
D.leavingtheearthandenteringtheorbit
根据上面一段话选答案
==。。。。三个不同的答案。。。。