2 sentences

1. 他们俩从小就在一起，关系亲密无间。

   tā​men liǎ cóng xiǎo jiù zài yī​qǐ, guān​xi qīn​mì​wú​jiàn.

   The two of them have been together since childhood and are extremely close.

   Source: Dong Chinese Dictionary

2. 这种拼合工艺要求极高，接缝处几乎无间。

   zhè zhǒng pīn​hé gōng​yì yāo​qiú jí gāo, jiē​fèng chù jī​hū wú jiàn.

   This jointing process is highly demanding, and the seams are almost seamless.

   Source: Dong Chinese Dictionary