1）what = the thing which；whatever = anything。例如：
What you want has been sent here. 你要的動詞都送來了。
Whatever you want makes no difference to me. 不管你要什麼，跟我沒什麼關係。
2）who= the person that whoever= anyone who。例如：
（錯）Who breaks the law will be punished.
（錯）Whoever robbed the bank is not clear.
（對）Whoever breaks the law will be punished. 王子犯法，與庶民同罪。
（對）Who robbed the bank is not clear. 誰搶了銀行還不清楚。