碱性条件下高铁氰化钾可将其氧化为具有兰色荧光的硫色素，据此，可用以对（）进行定量测定。
A.叶酸
B.硫胺素
C.生物素
D.核黄素
参考答案：B
— How is Yangzhou Taizhou Airport going ?
— _______. [ ]
A. To say is easier than to do
B. Better late than never
C. So far, so good
D. The more, the better
The managers, ____it clear to us that he didn’t agree with us, left the meeting room.
A．who has made
B．having made
C．made
D．making
