Some doctors doubt the possibility of donor hearts being replaced by artificial ones

A. can
B. have to
C. need to
D. should

A. speak
B. have
C. have
D. have

A. B股
B. A股
C. 基金
D. 债券

A. 机构开户所使用的名称
B. 机构专用
C. 机构所使用的交易席位号
D. 交易席位所属的公司名称