I, O, U.

注：I，O，U三个元音组成单词IOU，意思是“借据”（由I owe you 的读音缩略转义而成）。

更多英语谜语

What animal took the most luggage into the Ark and what animal took the least?

What are the largest ants in the world?

What can have hundreds of limbs but can't walk？

What breed of dog has no tail?