【单选题】Which one of the following cohesive devices are NOT used in the sentences “Electricity is a convenient form of energy. It is well known that when fuels such as coal, oil and gas are burned, energy is...
【简答题】Scientists have long believed one way to stop the Earth’s atmosphere from warming is by planting more trees. The idea is that more trees will take in or absorb some of the carbon dioxide in the atmosp...