下列胃癌的病理类型，最少见的是（）。

A. * * 状腺癌

B.管状腺癌

C.低分化腺癌

D.印戒细胞癌

E.鳞状细胞癌

The reason why he succeeded is ______ he worked very hard.

A．why

B．that

C．whether

D．how