As he( )up since 4 a.m. , he is, no doubt, very tired now.
A.正确答案Cis
B.was
C.has been
D.had been
As he( )up since 4 a.m. , he is, no doubt, very tired now.
As he( )up since 4 a.m. , he is, no doubt, very tired now.
A.正确答案Cis
B.was
C.has been
D.had been