I always regret not         harder when I was young .
#97664
A
studying
B
having studied
C
to study
D
to have studied
推荐题目
Having lost his key,________.
#91037
A
he couldn’t enter the room
B
the gatekeeper offered to help
C
the door was forced open
D
the room couldn’t be entered
She caught the student ______ in the exams.
#88508
A
to cheat
B
cheat
C
cheating
D
cheated