请教GWD 29-27

没办法1987

Since the gel contains zinc in the same form and concentration as the lozenges, the greater effectiveness of the gel must be due to the fact that cold viruses tend to concentrate in the nose, not the mouth.

结论说：因为gel和lozenges两者的zinc含量和形式的一样的，所以影响药效的原因只能是“服药方式”（假设：只有这两种因素）

D:
            Whether either the zinc gel or the lozenges contain ingredients that have an impact on the activity of the zinc.（是否有第三种因素影响药效）

 

如果是YES, 就是说这两种药因为有其它的
                ingredients 引起了药效不一样,那么就不能说是“服药方式”影响药效了.、

 

B说，是否有不含 zinc 的口服药能治疗。文章说的方法是“鼻子”影响，而非“口服”没影响。

要找准文章论断主线