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