m的平方的2倍与n平方的差，用代数式表示为______．
m的平方的2倍与n平方的差，用代数式表示为2m2-n2．
故答案为：2m2-n2．
The plant is dead. I _____ it more water.[ ]
A. will give
B. would have given
C. must give
D. should have given
