)didtherealizethathehadmadeamistake.
A.Uponenteringtheclassroom
B.Onlyafterenteringtheclassroom
C.Afterhehadenteredtheclassroom
D.Assoonasheenteredtheclassroom
On(Opon)ingUponenteringtheclassroom,herealizedthathehadmadeamistake.这句话对吗?