我完全看不懂。

That was all Greek to me.

Source: Tatoeba

Sentence Composition

1 我 wǒ
  1. I
  2. me
  3. my
2 完全 wánquán
  1. complete; whole
  2. totally; entirely
=3 看不懂 kànbudǒng unable to make sense of what one is looking at
=3 看不懂 kànbùdǒng to not understand (when reading, viewing or watching)