3 sentences

1. 我们还没定下结婚的日子。

   wǒ​men hái méi dìng​xià jié​hūn de rì​zi.

   We haven't set a date for the wedding yet.

   Source: Dong Chinese Dictionary

2. 经理为这次会议定下了基调。

   jīng​lǐ wèi zhè cì huì​yì dìng​xià le jī​diào.

   The manager set the tone for the meeting.

   Source: Dong Chinese Dictionary

3. 鼓手定下了这首曲子的节奏。

   gǔ​shǒu dìng​xià le zhè shǒu qǔ​zi de jié​zòu.

   The drummer set the tempo for this piece.

   Source: Dong Chinese Dictionary