— Does your aunt usually walk the dog in the park?

— Yeah,                bad weather stops her.

A．when

B．since

C．unless

D．if

茧唇的发生与以下哪项无关？（）

A.长期吸烟

B.口唇白斑

C.口唇赘疣

D.遗传因素

E.皲裂长期不愈