女，28岁，已婚，经常饮酒、吸烟，近半年来频发不明原因低热，近端指间关节肿痛，经医院检查疑是SLE，女性多患此病的原因是（）

A.与吸烟有关

B.与饮食有关

C.与雌激素有关

D.与饮酒有关

E.与婚姻有关

In our class, when the bell rang and the teacher closed his book, it was a____ for everyone to stand up. [ ]

A. signal      

B. chance    

C. mark    

D. measure