he has five children,and---of them os good at painting

everyone是一个词,只用来指人,等于 everybody,在它后面不能跟介词of； every one是两个词,既可用来指人,也可用来指物,等于each one,后面可跟介词of D更不可能了,是形容词吧.
everyone每人
everybody每人,大家,人人
复合不定代词只相当于名词,在句中用作主语、宾语和表语