I don't quite know what to say. 我不太知道该说什么。
I didn't quite catch what he said. 我没太听懂他说的话。
I still don't quite understand what's happening.
She didn't quite know what all the fuss was about.
I'm afraid I didn't quite grasp the rules.
"Is this the color you were thinking of?" "Not quite? I think it's close, though."
She didn't quite get it at first, but after I'd explained what I was doing, she got a better idea.
See also: quite adverb