Has ____ how many spies we caught during the war ____ up to now?

A．it been declared; have been set free

B．it declared; have been set free

C．they declared; has been set free

D．they declared; have set free

关于卵巢无性细胞瘤，下列哪一项是错误的（）。

A.卵巢恶性生殖细胞实性肿瘤

B.常见于儿童及青年妇女

C.肿瘤彩色多普勒血流显像可显示丰富血流

D.卵巢实性良性肿瘤

E.卵巢少见肿瘤