A forest is full of many diffrent kinds of trees-they are all sizes and shapes and shades of color. It is hard to imnagine a pind tree wishing it  ①were an oak. Instead, each tree catches raindrops and reflects and sunshine in its own way. We often find ourselves ②enving others. We think they have more money or more friends. We see them as better looking or luckier in some way than we are. It is ③so easy to overlook our own gifts when we do this. We get fooled by what looks good and forget that all human being have some weaknesses and pain, just as we ④are. Like the trees in the forest, we each have our own unique beauty and talents.  If we believe in ⑤ourselves, rather than envy those around us, we will grow green and tall in our own way.

여기서 답은 4번이던데 왜그런가요 그리고 나머지 문법도 설명좀해주세요 3번은 too to 용법 아닌가요 ㅠㅠ ? 자세히부탁드려요!!