I don't understand

I don't understand (it)

I'm confused or puzzled (by something). I don't understand why Tom would make such a ridiculous statement. Honey, I just don't understand—why are you so upset? I don't understand it, but yes, Sue is selling her beautiful house.

See also: understand

I don't understand (it).

 and I can't understand (it).

I am confused and bewildered (by what has happened). Bill: Everyone is leaving the party. Mary: I don't understand. It's still so early. Bob: The very idea, Sue and Tom doing something like that! Alice: It's very strange. I can't understand it.

See also: understand