____some doubt among scientists about the cause of cancer.
#92930
A
It exists
B
There exists
C
There is existing
D
It is existing
推荐题目
As a boy of six, .
#93476
A
Tim’s parents asked him to play the piano every day.
B
Tim and his parents would play the piano together.
C
Tim had to practice playing the piano every day.
D
to learn playing the piano is too hard for Tim.
I would appreciate ______ you could give me some advice on TOFEL test.
#91939
A
that when
B
it whether
C
it if
D
that if