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:
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 both shut off valves
Open both shut off valves
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