尽管老师耐心解释了三遍，这个厚脑袋的学生还是没明白这道数学题。

Even after the teacher explained it three times, the ___thick-skulled student still didn't understand the math problem.

无论我们怎么暗示他都不明白，真是个榆木脑袋。

No matter how we hinted, he couldn't understand—what a ___thick-skulled person.