三年级上册英语课件-UNIT 3 LET'S DO MATH LESSON 17 课件｜清华版（一起） (共15张PPT)

UNIT 3 LET’S DO MATH LESSON 17 20~90的十位数的整数均以后缀-ty结尾 20 twenty 30 thirty 40 forty 50 fifty 60 sixty 70 seventy 80 eighty 90 ninety Again 20 30 40 50 60 twenty thirty forty fifty sixty 70 80 90 100 seventy eighty ninety one hundred Let’s do it There are forty bananas. My brother took away ten. How many bananas are left? 40-10=30 Forty minus ten is thirty. Thirty bananas are left. There are fifty apples. My sister took away twenty. How many apples are left? 50-20=30 Fifty minus twenty is thirty. Thirty apples are left. There are fifty eggs. My mother took away thirty. How many eggs are left? 50-30=20 Fifty minus thirty is twenty. Twenty eggs are left. There are sixty pears. My father took away ten. How many pears are left? 60-10=50 Sixty minus ten is fifty. Fifty pears are left. Practice 1. 90-20=? 2. 80-20=? Ninety minus twenty is________. Eighty minus twenty is________. One hundred minus twenty is________. 3. 100-20