2 sentences

1. 他对感情非常专一。

   tā duì gǎn​qíng fēi​cháng zhuān​yī.

   He is very faithful in his relationships.

   Source: Dong Chinese Dictionary

2. 学习要专一，不能三心二意。

   xué​xí yào zhuān​yī, bù néng sān​xīn'èr​yì.

   You must focus on your studies and not be half-hearted.

   Source: Dong Chinese Dictionary