blind alley

blind alley
1 alley that is closed at one end; cul-de-sac 仅有一端与外间相通的小巷; 死胡同.
2 (fig 比喻) course of action which may seem promising at first but which in the end has no satisfactory result 起初似乎大有希望, 而结果却不能令人满意的做法; 钻死胡同.

牛津英汉双解词典