There is still quite a long way to go （） researchers can find a solution to the problem.
A.正确答案Abefore
B.until
C.so
D.where
There is still quite a long way to go （） researchers can find a solution to the problem.
There is still quite a long way to go （） researchers can find a solution to the problem.
A.正确答案Abefore
B.until
C.so
D.where
