1. Had it not been for a famous film star attended, the party wouldn't have been a success.

2. No sooner had he left the office than the telephone rang. 

3. Only when their second child was born did Alice and Charles decide to move to a bigger house. 

4. Should the river rise any higher, the town will be flooded.

5. Were I you, I'd accept the offer.

6. Were the chemical leaked, a large area of the sea woud be contaminated.

7. Had it not been for Henry, I might not have met you.

8. Never does Tom seem worried about his future.

9. Not until we're certain it's true will we tell anybody the good news. 

10. Near the old pagoda there js a red flower.

11. So gracefully did the dancer move that he appeared to be skating. 

12. Such an ignorant girl she is that she has never paid any attention to any boys.

13. Under no circumstances should you park on double yellow lines.