This problem may lead to more serious ones if ______ unsolved.
#67907
A
making
B
remained
C
keeping
D
left
推荐题目
You're the only person ______I've ever met ______could do it. 
#73843
A
who;/
B
/; whom
C
whom;/
D
/; who
Make marks _______ you have questions. 
#66894
A
which
B
in which
C
where
D
in where
He has made another wonderful discovery,___ of great importance to science.
#73562
A
who I think it
B
which I think it is
C
that I think is
D
which I think is