'used to be' means it was in the past, but isn't anymore. Example: "The neighbours added an extension to their house, and now the space between our houses isn't as big as it used to be." NOTE: AS big AS it used to be So your sentence should read: "The environment is no longer AS clean AS it used to be." (The capitals are for emphasis only. This is a comparative.) "It is used" Is using the verb 'to use', and this is a passive structure. "The machine is used to make car doors." (passive) "We use the machine to make car doors." (active)

The environment is no longer AS clean as it used TO BE. (1) To make a comparison, you need two AS: Today isn't AS cold AS it was yesterday. (2) The verbal phrase USED TO must always be followed by a verb in the plain infinitive form: I used to WORK for her father. This is the hotel where I used to WORK. Our teacher isn't as nice as he used to BE. ______________________ Hope this helps. Happy New Year!