钻牛角

zuān niú jiǎozuanniujiao

1. lit. honing a bull's horn; fig. to waste time on an insoluble or insignificant problem
2. to bash one's head against a brick wall
3. a wild goose chase
4. a blind alley
5. to split hairs
6. same as idiom 鑽牛角尖|钻牛角尖

Study it in Yanamino