Put the verbs in brackets into the past simple or past continuous. 3 When Helen (walk) to school, she (see) the old man again.

When Helen **was walking** to school, she **saw** the old man again.
Explanation: The action of walking was in progress when she saw the old man again. So, for walking, we use the past continuous, 'was walking'. The action of seeing the old man is a simple completed action and it is in the past simple, 'saw'.