Choose the correct form of the verb. 
1. I … him before we met at the concert. 
a) didn't see b) wasn't seeing c) hadn't seen 
2. When mother came home, the children … the soup. 
a) ate b) were eating c) had eaten 
3. The telegram … some minutes after he had left. 
a) came b) was coming c) had come 
4. While we … the road I saw Victor. 
a) crossed b) were crossing c) had crossed 
5. When … your sister … to London? 
a) did … go b) was … going c) had gone