Matching Pairs Past Continuous: When ( Stopwatch4B, Workbook, exercise 3, page 144)Online version Matching pairs by Andronica Ribera Moruco 1 They were studying for a math exam 2 He was riding his bike 3 She was walking her dog 4 She was doing yoga when the earthquake started. when someone knocked at the door. when his telephone rang. when she saw an accident.