A new case study says Chinese companies face tough _____in the US and have a long way to go to be successful.

A．challenges

B．campaigns

C．motivations

D．dilemmas

能分泌雄激素

A．库肯勃瘤
B．卵泡膜细胞瘤
C．卵巢支持细胞一间质细胞瘤
D．绒毛膜癌
E．内胚窦瘤