△ABC的三边a、b、c,若满足b2=a2+c2,则( )=90°;若满足b2>c2+a2,则∠B是( );若满足b2<c2+a2,则∠B是( )。
∠B,钝,锐。
Barry must have visited the Eiffel Tower before, _____ he?[ ]
A. mustn't
B. hasn't
C. didn't
D. needn't
班组经济核算的内容有劳动核算、()核算、成本核算。
A.经济效益
B.材料消耗
C.计划指标
D.生产成果