Scientists have created GM tomatoes which ______ fresh for 45 days, three times as long as normal tomatoes.

A．are stayed

B．have been stayed

C．stay

D．stayed

供应链项下应收账款质押的买方基本条件包括（）。

A、各产业链上的核心企业

B、地方重点企业或行业龙头企业

C、优质上市企业

D、世界500强企业

E、中国500强企业