I often visit my parents, who live in the countryside  whenever ____.

The islands developed on their own for 80 million years and ________ have many rare animals found nowhere else. 

We must stop pollution _____ longer. 

.This printer is of high quality and very expensive. ________, we would buy __________.

Teterboro is the same airport where a plane took off earlier this morning before colliding (碰撞)with a sightseeing helicopter over the Hudson River.