Choosen As Best Answer
4. 你的原句：He didn't wait the bus, instead take the taxi go to school.
He didn't wait for the bus and took the taxi instead to go to school.
或者用instead of 來造
Instead of waiting for the bus, he took the taxi to go to school.
Not waiting for the bus, he took the taxi to go to school instead.
5. 原句 This area has four-fifths over population to us Taiwanese for mother tongue
"這個地區五分之四以上的人口"(這是一個大主詞) + 使用 (use為主要動詞) + 台語 為母語
"Over four-fifths of the population in this area" uses Taiwanese as mother tongue.