In ①_______ ________, people lived in a clean environment. There were not many factories or cars. ②_______, the air and water were not dirty.

 Today, there are ③________ factories and cars _______ before. They spoil water and air. People make a lot of trash and ④________ it ________, too. People ⑤________ enjoy fresh air and clean water.

 Now people want to live in a clean environment again. Factories and cars make ⑥________ pollution _________ before. People want to recycle old things. So, they don't make much trash.