Unemployment difficulties ckearky have an impact on people's emotional and ___.

A recent survey said ___ that cause the ozone destruction had increased since the eruption of Mount Pinatubo.

The latest ___ suggests that seaweed-based treatments could cure all kinds of medical conditions.

___ over the past decades have drastically reduced the price of computers and other electronic products.

Scientists have used ___ to protect tomatoes against the effects of freezing.