原式=x+1(x+2)(x+1)-x+2(x+1)(x+2)
=x+1-(x+2)(x+1)(x+2)
=-1(x+1)(x+2)．
There ____a computer on their desks in the future.
A. will have B. will be C. will has
在抗生素微生物检定法中，实测效价与估计效价：试验计算所得效价应在估计效价的正负（）以内。
