wild-goose chase

1. N-COUNT If you are on a wild goose chase, you waste a lot of time searching for something that you have little chance of finding, because you have been given incorrect information. (根据错误信息进行的)白费力气的寻找[usu 'on' N]

Harry wondered if Potts had deliberately sent him on a wild goose chase. 哈里怀疑波茨故意派他出去瞎找一番。