cutting down trees是__动__词短语在句子中作__主__语,谓语用_单__数.
散步是我的爱好.__Walking____ __is____my hobby
打乒乓球很有意思._Playing__ __table-tennis__ _is__great fun
阅读使人完美._Reading____ __is__ _making__a man __perfect__.
Although we have buit"the great green wall",we still need to work hard to protect the environment.（翻译）
尽管我们已经建立了“绿色长城”,但是我们仍需要努力保护环境.