2 sentences

1. 这是一个包含两个未知数的二元方程。

   zhè shì yī gè bāo​hán liǎng gè wèi​zhī​shù de èr​yuán fāng​chéng.

   This is a linear equation with two variables.

   Source: Dong Chinese Dictionary

2. 这种经济模式呈现出明显的城乡二元结构。

   zhè zhǒng jīng​jì mó​shì chéng​xiàn chū míng​xiǎn de chéng​xiāng èr​yuán jié​gòu.

   This economic model shows a clear dual structure between urban and rural areas.

   Source: Dong Chinese Dictionary