Choose the best option to complete each sentence below

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IV. Choose the best option to complete each sentence below:
1. The tourists cleared up the beach ……….. they got back to the hotel.
A. after B. while C. before D. if

2. Please call us ……….. you have troubles.
A. whenever B. while C. until D. no sooner as

3. Don’t worry! I will watch ……….. you are swimming in the lake.
A. after B. since C. until D. while

4. ……….. the conservationists arrived, they started to look into the injured animal.
A. Until B. As soon as C. Before D. whenever