上消化道出血病因诊断的首选检查是（）

A.粪便隐血实验

B.选择性腹腔动脉造影

C.电子胃镜

D.消化道X线钡餐检查

E.腹部B超

It is generally agreed that a red sky at night      that the following day will be fine weather. [ ]

A. announces

B. indicates

C. declares

D. permits