You can, ________ the sky is clear, see as far as the old temple on top of the mountain, but not today.[ ]

A. because  

B. though

C. for  

D. when

膀胱肿瘤分期的标准是根据下列哪一项（）。

A.肿瘤大小

B.临床症状

C.有无肾积水

D.肿瘤侵犯膀胱壁的深度

E.肿瘤部位