請幫我講解一下英語單詞的用法.

題目：

請幫我講解一下英語單詞的用法.
1 percent percentage
2add addition addtional
3confusing confused confusion
4complain complaint
另外請幫我講解一下表語從句的語法!
還有other states have a sales tax,which is charged to any item which you buy in that state.這個句子中爲什麼用to!

解答：

to表實方向,表稅收追加在你在那個你買物品的州里