A. zebra crossing B. in trouble C. hello D. porcupine A. pavement B. emission C. face D. get into the habit of A. safe B. baleen C. cooking D. nature shows A. air hostess B. rule C. regard as D. squeeze A. safely B. cart C. ups and downs D. bleed A. blow up B. guest C. convention D. safety A. outside B. rubble C. spell D. follow A. dismantle B. wash away C. road D. laughter A. limit B. flat C. hardship D. must A. look out for B. undue C. melon D. assignment