问题
填空题
读一读，按规律写数字。
1. one, __________, __________, seven, __________
2. fifty-one, __________, seventy-one, eighty-one
3. twenty, __________, forty __________, sixty __________ __________
4. thirty-five, __________, __________, fifty-seven, sixty-eight, __________
答案
1. three, five, nine 2. sixty-one, ninety-one 3. thirty, fifty, seventy, eighty 4. forty-six, seventy-nine