He failed in the exam, and I wonder ___ he studied hard in the school.
#80339
A
when
B
that
C
if
D
where
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________ in his book, he didn't notice me ________ I entered the room.
#29957
A
Devoted; when
B
Absorbed; while
C
Absorbed; when
D
Devoted; while
__________ he took part in the competition, he won a second prize. 
#33676
A
The first time
B
For the first time
C
At a time
D
At one time