结构中含有吲哚环的药物是（）

A.喜树碱 

B.依托泊苷 

C.紫杉醇 

D.阿霉素 

E.长春新碱

When a party to a forward contract terminates the contract prior to the original expiration date by entering into a perfectly offsetting forward contract with a second counterparty:()

A. the party terminating the forward contract has no default risk, but both counterparties face default risk. 

B. there is no future liability, but default risk remains for all parties until the original contract settlement date. 

C. the party terminating the contract is exposed to default risk, but has no further asset price risk.