高炉炼铁的过程是使氧化铁还原，获得生铁的过程。
参考答案：对
若函数y=f（2x+1）的定义域为[1，2]，则f（x）的定义域是（ ）
A．[3，5]
B．[1，5]
C．[0，3]
D．[0，0.5]
We don't have much homework now and our school bags are ______ they used to be. [ ]
A. as heavy as
B. not as heavy as
C. as heavily as
D. not as heavily as
