sentence: In the past , cars were only affordable for the upper classes , while for the middle class and lower there were not many choices for them besides walking and public transportation .
modified: In the past , cars are only affordable for the upper level while for the middle class and lower there are not many choice for them beside walk and public transportation .
transformation: VERB:TENSE, OTHER, VERB:TENSE, NOUN:NUM, PREP, VERB:FORM