One addend adds one number. The other addend subtracts the same number. The sums are the same.
One addend adds one number. The other addend subtracts the same number. The sums are the same.
小结：一个加数增加几，另一个加数减少几，增加和减少的数相等，它们的和仍是10。
One addend adds one number. The other addend subtracts the same number. The sums are the same.
小结：一个加数增加几，另一个加数减少几，增加和减少的数相等，它们的和仍是10。