---You don’t often see them, do you? ---No, I see of them.
The experiment shows that proper amounts of exercise, if _______ regularly, can improve our health.
When I opened the door, I found my father sitting in his chair, completely ______ in the humorous stories he was reading.
______ money, his parents couldn’t send him to university.
It’s very dangerous to _______ these viruses without any protection.
My father is always strict _______ me, so he was very angry _______ my fault on this matter.