二年級(jí)口算題：整十?dāng)?shù)加整十?dāng)?shù)的加法

二年級(jí)口算題：整十?dāng)?shù)加整十?dāng)?shù)的加法
    （1）70 + 30 =
    （2）70 + 30 =
    （3）70 + 50 =
    （4）50 + 40 =
    （5）40 + 90 =
    （6）60 + 20 =
    （7）70 + 70 =
    （8）40 + 80 =
    （9）30 + 70 =
    （10）50 + 70 =
    （11）20 + 50 =
    （12）60 + 10 =
    （13）30 + 50 =
    （14）10 + 40 =
    （15）80 + 70 =