(1) Through the 1990s, the average weight of Americans increased by 4.5kg ... (2) More than half - 56 per cent - of US adults were overweight or obese in the early 1990s ... This rose to 65 per cent in a similar survey done from 1999 to 2002. Be careful with the preposition you use when talking about an increase or a decrease. In (1), the increase in average weight is 4.5kg. If we say 'the average weight increased to 4.5kg', it means something completely different: that the average weight was 4.5kg. In (2), the increase is from 56 per cent to 65 per cent, an increase of 9 per cent. 1. Read lines 15 to 19: 'The extra weight ... Preventive Medicine.' This means an increase __ 1.32 billion in the litres of fuel burned in 2000. 2. Read lines 23-26: 'The extra fuel ... the study.' This means the amount of carbon dioxide released into the air rose ___ 3.8 million tonnes. Answers: of, by
