It is a pity that we have to ___________ the school trip because of the rainy days.

  560（ ）8=70              48（ ）52=100              35（ ）9=315

  5（ ）600=3000            260（ ）4=1040             999（ ）1=999

803（ ）2=1606            888（ ）0=0

双曲线$\frac{x^2}{m^2+12}-\frac{y^2}{4-m^2}=1$的焦距是（   ）