If we work hard with a strong will, we _____ overcome any difficulty, however great it is.[ ]

A. must

B. need

C. should

D. can

接触性皮炎与急性湿疹的鉴别哪项错误（）

A.皮疹是否境界清楚

B.皮疹是对称发生

C.皮疹是否单一形态

D.皮疹是否瘙痒

E.病因是否明确