ГДЗ граматика Англійська мова 7 клас Мітчелл

Complete with the Past Simple or the Past Progressive of the verbs in brackets. 

Last night Darren (1) was running in the park when suddenly he (2) did not feel very well. He (3) couldn’t go on running, so he (4) decided to go home. As soon as he (5) arrived, he (6) realised that the lift (7) was not working, so he (8) took the stairs. While he (9) was climbing up the stairs carefully, he (10) tripped and (11) fell down. 'What a day!' he (12) thought.