维生素B2的良好来源是（）。
A.白菜
B.菠菜
C.小麦
D.动物肝脏
E.油菜
参考答案：D
客户持同一借记卡可以对应（）个债券托管账户。
A.1
B.2
C.3
D.5
So many directors ________, the board meeting had to be put off.
A．were absent
B．been absent
C．had been absent
D．being absent
