("0".."10").to_a.join(" and ")
って見れば普通は、
["0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", " and "]
ってなるだろーなーと思うわ。

("0".."10").to_a.concat(" and ")
なら、
"0 and 1 and 2 and 3 and 4 and 5 and 6 and 7 and 8 and 9 and 10"
でもいい。