投资者购买可转换债券，表明投资者可在一定时期内将其转换为（）

A.收益较高的新发行债券

B.普通股

C.优先股

D.其他有价证券

Catherine is one of the brightest students who     from the Department of Computer Science , Brown University .

A．is graduated

B．has graduated

C．are graduated

D．have graduated