—Sure it is! The government ________ have made great efforts!
A:could
B:should
C:might
D:must
已知函数f(x)=x2﹣kx﹣8在区间2,5上具有单调性,则实数k的取值范围是____
如图,△ABC≌△ADE,∠DAC=60°,∠BAE=100°,BC、DE相交于点F,则∠DFB的度数是( )