1. _______refer to biodegradable products, i.e. they break down rather quickly. 2. The handling of solid waste _______ a serious problem. 3. I think that ______ _______ ________ won’t do much good because it is interference in natural laws. 4. The grass was littered with _______ cans and cardboard boxes. 5. It is universally known that polar bears ______ upon seals. 6. The ancient _______ system of this town is in a perfect state. 7. Last year we reaped good _______ of apples, pears and quinces. 8. I think the factory violates the law _______ garbage near our residential area. 9. This area is rich in natural gas
deposits.
___ crops have been controversial in the scientific community for years.