The government has been under growing pressure to ________ the causes of air pollution as smog frequentlysmothers the country’s large cities

ecial thanks go to thousands of volunteers,without ________tireless work, none of this would be possible

_____ many times, but he still doesn’t know how to operate the machine properly

Layingeggsthe ant queen’s full-time job.

_______ review off 44 studies,American researchers found that men and women who ate six key foods daily cutthe risk of __________ heart disease by 76%. _______