_________ you have tried it on, you can't imagine how pretty the new style skirt is.[ ]

A. Because          

B. Although

C. Unless            

D. When

佝偻病的发病原因是（）.

A.先天禀赋不足

B.反复感受外邪

C.喂养不当

D.日照不足

E.跌仆损伤