_________ that he had fallen behind, he tried to work harder. 
#96219
A
Realize
B
Realized
C
To realize
D
Having realized
推荐题目
My friend Jack was the first person I knew ______an iPhone 5S.
#89592
A
using
B
to use
C
used
D
having used
At the routine office meeting, the headmaster insisted that the problems _______ paid special attention to.
#90590
A
referred to being
B
referred to be
C
refer to being
D
refer to be
______ late in the morning, Bob turned off the alarm.
#98804
A
To sleep
B
Sleeping
C
Sleep
D
Having sleep