1 sentence

1. 没有人确切知道人脑中神经元的平均数量。

   méi​yǒu​rén què​qiè zhī​dao rén nǎo zhōng shén​jīng​yuán de píng​jūn shù​liàng.

   No one knows for sure the average number of neurons in the human brain.

   Source: CCMatrix