1 By the time Graham arrived at the train station, the train had already left.
2 How long had you been trying to call Tom before he finally answered the phone?
3 The children had put away their toys before their mum came back home.
4 Alan had a headache because he had been playing computer games all afternoon.
5 Simon had been saving money for many years before he bought his own house.
6 The football game had just started when it began to rain.