1 sentence

1. 老教授背着手在实验室里走来走去。

   lǎo jiào​shòu bèi​zhe​shǒu zài shí​yàn​shì lǐ zǒu​lái​zǒu​qù.

   The old professor walked around the lab with his hands behind his back.

   Source: Dong Chinese Dictionary