sentence: Firstly , travelling by bus or on other public transport , such as the underground , helps us to decrease the emission of exhaust which causes pollution and global warming .
modified: Firstly , travelling by bus or in other public transport,(as underground ) , help us to decrease the emissions of gas , which causes pollution and global warming .
transformation: PREP, OTHER, DET, PUNCT, VERB:SVA, NOUN:NUM, NOUN, PUNCT