1 When we arrived at the stadium, the race had started.
a The race was in progress when we arrived at the stadium.
b The race started after we arrived.
2 Louise had done a lot of training when she took part in the tennis competition.
a Louise first did a lot of training and then she took part in the tennis competition.
b Louise did a lot of training at the same time that she took part in the tennis competition.
3 The record company had to pay back all the money to the people that had bought tickets.
a The record company paid the money first and then people bought tickets.
b People first bought tickets and then the record company paid the money.
4 He told everyone that he had won a gold medal.
a He won a gold medal and at the same time told everyone.
b He first won a gold medal and then he told everyone.
2.b
3.b
4.b
Мне кажется, что так, но я не уверена на все 100%