二年級數(shù)學整千數(shù)的減法口算題

（1）6000 - 5000 =
    （2）7000 - 3000 =
    （3）7000 - 3000 =
    （4）9000 - 6000 =
    （5）9000 - 3000 =
    （6）2000 - 1000 =
    （7）9000 - 8000 =
    （8）9000 - 1000 =
    （9）2000 - 1000 =