sentence: I started this hobby in 2007 , and since then I have tried to have many different kinds of singing birds . I spend one day in the week taking care of them , feeding them , cleaning the cages , changing the water .
modified: I 've started this hobby since 2007 , and since then I have tried to have many different kinds of the singing birds , I spent one day in the week to take care of them , feeding them , cleaning the cages , change the water .
transformation: CONTR, PREP, DET, PUNCT, VERB:TENSE, VERB:FORM, VERB:FORM