Some of the smartest answers come after the longest silence.
Back when I was studying Mandarin, I used to pause before answering questions. It wasn’t because I didn't get it, it was because tone selection, pinyin decoding, and meaning all needed a second to align.
Thinking speed is not comprehension speed. Give people time to speak!
It does not matter how slowly you go as long as you do not stop.— Confucius.
Some students need more time to answer. That doesn't mean they don't understand. Thinking speed and understanding are not the same thing.
Give them time.