He often helps the students _______ he thinks are not quick at their studies. 
#69855
A
whom
B
who
C
when
D
because
推荐题目
 He fell off the bike ________.
#41254
A
while he rode
B
while he was riding
C
while he is riding
D
while on bike
The clock was striking twelve ______ down the street. 
#74557
A
because I walked
B
as I walked
C
since I was walking
D
while I was walking