一道open 这道题该选什么?Some new oil fields ( ) since 1976.A.were opened up B.have been opened up C.has opened up D.have opened up可是为什么不是B,而是D呢?

一道open 这道题该选什么?Some new oil fields ( ) since 1976.A.were opened up B.have been opened up C.has opened up D.have opened up可是为什么不是B,而是D呢?
一道open
这道题该选什么?
Some new oil fields ( ) since 1976.
A.were opened up B.have been opened up C.has opened up D.have opened up
可是为什么不是B,而是D呢?

一道open 这道题该选什么?Some new oil fields ( ) since 1976.A.were opened up B.have been opened up C.has opened up D.have opened up可是为什么不是B,而是D呢?
open up是展开,揭露,的意思
翻译:自从1976年,新的油田逐渐出现了.
而不用被动(出现是本身属性)
若用被动