1. three nine five six four ten eleven eight 从小到大: 2. eighteen fifteen seventeen twenty thirteen 从大到小: 3. four seven ten six three fourteen nine five 写双数:
1. three + six = __________ 2. __________ - two = eight 3. five + three = __________ 4. one, __________, five, seven, __________ 5. two, __________, six, __________, ten