The past two years ________ a sharp rise in oil price，which adds to the burden of auto transportation industry.

A．witnessed

B．has witnessed

C．is witnessing

D．witnesses

排卵前分泌孕激素的是（）

A.颗粒黄体细胞

B.卵泡颗粒细胞

C.始基卵泡

D.卵泡膜黄体细胞

E.肾上腺皮质