Carbon dioxide is one of the primary greenhouse gases that cause global warming.

A. We decided to reduce carbon footprints before seeing people suffer global warming consequences.

B. We saw people suffer global warming consequences after we decided to reduce carbon footprints.

C. We decided to cut down on carbon footprints after we saw people suffer global warming consequences.

D. We decided to cut down on carbon footprints before we saw people suffer global warming consequences.

A. Heat-related illnesses result from the increase in earth's temperature.

B. Heat-related illnesses result in the increase in earth's temperature.

C. Heat-related illnesses lead to the increase in earth's temperature.

D. Heat-related illnesses trigger the increase in earth's temperature.

A. Global warming can't be controlled by planting trees.

B. Planting trees is the only way to control global warming.

C. Planting trees can accelerate global warming.

D. Planting trees can help reduce global warming.

A. Some scientists were accused of having falsify the effects of climate change.

B. Some scientists were accused of having been honest about the effects of climate change.

C. Although some scientists have distorted the effects of climate change, they were not accused.

D. Some scientists were accused of having falsified the effects of climate change.

A. Unless he donated a lot of money to environmental protection campaigns, he was admired.

B. He was admired for having donated a lot of money to environmental protection campaigns.

C. If he had donated a lot of money to environmental protection campaigns, he would have been admired.

D. If he donates a lot of money to environmental protection campaigns, he will be admired.

A. Having denied his company's damage, he took responsibility for it.

B. He denied having damaged to his company's area.

C. He denied having taken responsibility for the damage to his company's area.

D. He denied having said that he would take responsibility for his company's damage to the area.