1. .......... engaged in as competition ......... as recreation, waterskiing is an exhilarating outdoor sport.

2. Special heat sensors on the front of the rattlesnakes head enable it......... to detect the presence of prey in the dark ......... to strike its victim accurately.

3. Peter is leaving to go back to England, ....... we are holding a farewell dinner for him.

4. As we will be touring, we could take the tent just .......... we see a nice campsite and want to stop.

5. .......... urgently callers say they need to speak to me, I do not want any calls for the next hour.

6. ......... the work was physically demanding, and at times we felt really exhausted, seeing the end result was very satisfying.

7. He has put on a little weight ..........he started doing this sedentary office job.

8. It is a pebble beach, .......... we had better take some beach mats to lie on.

9. They looked around a lot of different buildings ........... they could choose the most suitable one to rent for their new business.

10. ......... he is a strong man, he had no trouble hiking with a heavy rucksack.