__________ you've got a chance, you might as well make full use of it. [ ]

A. Now that      

B. After    

C. Although    

D. As soon as

皮内试验出现假阴性，可能是由于（）

A.抗原变质或污染

B.抗原注入太深

C.患者有皮肤划痕症

D.变应原稀释液偏酸或偏碱

E.抗组胺药影响