为了提高计算速度，我们今天来学习一些加减法的简便运算。（板书课题）

We're going to learn the tricks of additions and subtractions in this class.

youdao

为了提高计算速度，我们今天来学习一些加减法的简便运算。（板书课题）

We're going to learn the tricks of additions and subtractions in this class.

youdao