Alternative sources of energy have environmental advantages. It’s not easy to make full use of them.

A. There had been warnings about the earthquake, so the people in nearby villages must not have been surprised by it.

B. Even though the earthquake had been predicted, residents of nearby villages were taken by surprise when it struck.

C. The earthquake having been predicted, even those inhabitants living in nearby villages were prepared for it.

D. The earthquake had been predicted, for the residents in nearby villages were struck before they received the warnings.

A. Because they have been working hard they are now very tired.

B. They must be very tired as they have been working all morning.

C. They can be very tired due to working all moming.

D. They were very tired because of a hard working moming.

A. That he smokes all the time I can’t stand.

B. What I can ’t stand about him is the way he smokes all the time.

C. I can ’t put up with what he smokes.

D. I can ’t bear his smoke.

A. A passer-by intervened just when a criminal was trying to attack Jane in the act of going home.

B. Had it not been for the intervention of a helpful passer-by, Jane would have been attacked on her way home.

C. If Jane hadn't got in the criminal's way home, a helpful passer-by would have been attacked.

C. If Jane hadn't got in the criminal's way home, a helpful passer-by would have been attacked.