等差数列{an}中，2a3-a72+2a11=0，数列{bn}为等比数列，且b7=a7，则b6b8的值为[ ]
A．2
B．4
C．8
D．16
答案：D
△ABC的一边为5，另外两边的长恰好是方程2x2-12x+m=0的两个根，则m的取值范围______．
— It is reported that there is big breakthrough in the cancer treatment.
— If only his son could be brought back to life! [ ]
A. a ; 不填
B. 不填 ; a
C. the ; the
D. a ; the
