We couldn’t help feeling disappointed when, after all our hard work, we had to close down the factory.
A.By working even harder we could, perhaps have managed to keep the factory open.
B.ỉf only we could have kept the factory going, we wouldn't have felt that all our work had been wasted.
C.Since we’d put in so much effort, it was inevitable that we should feel upset when we couldn't keep the factory going.
D.However hard we worked, we could not have stopped them closing down the factory.