满足下列条件的△ABC ,不是直角三角形的是 [ ]
A.b2=a2-c2
B.∠C =∠A- ∠B
C.∠A :∠B :∠C=3 :4 :5
D.a∶b∶c=12 :13 :5
C
The lawyer listened with full attention, ____ to miss any point. [ ]
A. not trying
B. trying not
C. to try not
D. not to try
运用供求关系原理分析说明石油输出国组织为什么要限制石油产量。