— Michael was late for Mr. Smith's oral class this morning.

— _____ ? As far as I know, he never came late to class. [ ]

A. How come

B. So what

C. Why not

D. What for

含亚铁盐地下水抽出地面后呈现（）

A.黄色

B.绿色或黄绿色

C.黄褐色

D.黑色

E.蓝色