The promise of finding long-term technological solution（ ）the problem of world food safety seems difficult to fulfill.
A.正确答案Ato
B.for
C.of
D.at
The promise of finding long-term technological solution（ ）the problem of world food safety seems difficult to fulfill.
The promise of finding long-term technological solution（ ）the problem of world food safety seems difficult to fulfill.
A.正确答案Ato
B.for
C.of
D.at
