CDL
Doubles and Triples
Practice Test

Question 3 of 3
Before you can supply the air tanks of a second trailer with air you need to:
Close both shut off valves
Open the shut off valve at the rear of the first trailer and close the shut off valve at the rear of the second trailer
Close the shut off valve at the rear of the first trailer and open the shut off valve at the rear of the second trailer
Open both shut off valves