If you are going to stay in the United States for longer than a(n) ______ visit, you may be interested in

learning more about its people and culture.[ ]

A. formal      

B. regular

C. brief    

D. unexpected

下列哪种方法的测定结果最接近于血中糖化血红蛋白的真值（）。

A.HPLC法

B.亲和色谱法

C.离子交换色谱法

D.等电聚焦法

E.电泳法