目前3A事件的迟滞值推荐为（）
A.1.5dB
B.2dB
C.2.5dB
D.3dB
参考答案：C
In the meantime, the question facing business is whether such research is ______ the costs.
A．worth
B．worth of
C．worthy
D．worthwhile
门静脉血流量约占肝血流量的百分之几（）
A.30%～39%
B.40%～49%
C.50%～59%
D.60%～69%
E.70%～79%
