2024 CO CDL Practice Test: Double and Triples - Test 2 Based on 2024 CO CDL Handbook 15. Where is compressed air stored? A In gas tubes. B In open grounds. C In sealed underground caverns. D In the vehicle. Next More 15/27 Progress 0 Errors Restart Next Next Double and Triples - Test 2 Back to Test List Double and Triples - Test Double and Triples - Test 3 Challenge Library 12 More CO CDL Practice Tests 26 Double and Triples - Test 3 27 Double and Triples - Test 4 28 Double and Triples - Test 5 29 Tank - Test 30 Tank - Test 2 31 Tank - Test 3 32 Tank - Test 4 33 Tank - Test 5 34 Air Brakes - Test 35 All - Test