6 sentences

1. 你觉得他们是兄妹吗？

   nǐ jué​de tā​men shì xiōng​mèi ma?

   Do you think they're brother and sister?

   Source: OpenSubtitles

2. 你们就像兄妹一样。

   nǐ​men jiù xiàng xiōng​mèi yī​yàng.

   You guys are like siblings.

   Source: OpenSubtitles

3. 他们俩是亲兄妹。

   tā​men liǎ shì qīn xiōng​mèi.

   The two of them are biological brother and sister.

   Source: Dong Chinese Dictionary

4. 我和她是兄妹。

   wǒ hé tā shì xiōng​mèi.

   She and I are brother and sister.

   Source: Tatoeba

5. 我们是兄妹。

   wǒ​men shì xiōng​mèi.

   We're brother and sister.

   Source: OpenSubtitles

6. 他们是兄妹。

   tā​men shì xiōng​mèi.

   They're brother and sister.

   Source: OpenSubtitles