No one knows for certain what happened, but it's a fair bet that it was not an accident.
没有人知道究竟发生了什么,但几乎可以肯定这并非意外。
Sam was sure that the wallet must have been found by one of the villagers, but it was not returned to him.
萨姆确信那钱包一定是被某个村民捡到了,可是却不见有人来送还给他。