if / environment / green / clean, / humen life / better
→ If the environment is green and clean, human life will be better.
if / air pollution / not decrease, / people / get / some / breathing problems
→ If air pollution doesn't decrease, people will get some breathing problems.
if / there / not / rubbish bin / in each classrom, / it / not / cleaner
→ If there is not a rubbish bin in each classroom, it will not be cleaner.