对肝硬化诊断有确诊价值的检查是（）。
A.X线钡餐检查
B.腹腔镜检查+活检
C.胃镜检查
D.腹部B超
E.腹部CT
参考答案：B
设集合A={x|x2-2ax+a2-1＜0}，B={x|x2-6x+5＜0}，若A∩B=∅，求实数a的取值范围．
The child was ____to go fishing alone because it was dangerous .
A．allowed
B．required
C．forbidden
D．encouraged
