The techniques now available to livestock breeders will continue to be ____ , but will probably be ___ by new ones under development.

A refined

D supplemented

B used

E downgraded

C fruitful

F reversed

选BD

翻译：现有的家畜养殖技术未来仍将发挥作用，但随着产业发展很可能补充新技术。

refine 精炼，提纯，改良，使更文雅、有教养

fruitful 肥沃的，结果实的，多产的

downgrade 降低(地位、程度、工资等)，贬低

reverse 逆转，取消，倒退，撤销或废除(法令等)