2 sentences

1. 动动脑筋，你一定能想到办法。

   dòng dòng nǎo​jīn, nǐ yī​dìng néng xiǎng​dào bàn​fǎ.

   Use your brains; you'll surely find a solution.

   Source: Dong Chinese Dictionary

2. 他的脑筋比较死板，不容易接受新事物。

   tā de nǎo​jīn bǐ​jiào sǐ​bǎn, bù róng​yì jiē​shòu xīn shì​wù.

   He is rather rigid in his thinking and doesn't easily accept new things.

   Source: Dong Chinese Dictionary