每周两次，孩子们接受基本数学技能测试，如加法和减法。

Twice a week the children are tested in basic math skills such as ___addition and subtraction.

加法是算术中的基本运算。

___Addition is a fundamental operation in arithmetic.

要找到总数，你需要进行加法运算。

To find the total, you need to perform ___addition.