John found it a challenge to meet the needs of the boss.      , he had no way to satisfy him.[ ]

A. In need    

B. In case  

C. In no time      

D. In other words

皮－Ⅲ型曲线是一条一端有限、一端无限、不对称单峰的（）曲线。

A.正偏

B.负偏

C.上升

D.下降