【答案解析】1. One of the effective ways to slow down global warming is to reduce the emission of greenhouse gases. 2. Learning each text by heart will not necessarily mean the ability to use English actively. 3. The fact that customs vary from country to country has to be taken into consideration. 4. What impresses me most is the changes that have taken place in China. 5. I have been wondering if the sentence can he translated in a better way.