header bg
8 arrow_forward 0 done arrow_forward 0 done_all

Should the shut-off valves on the first trailer in a set of doubles be open or closed?

A The shut-off valves on the first trailer should be open
Explaination
All shut off valves on the tractor and the trailers should be open, except for the valves at the rear of the last trailer.
B All shut-off valves should be open
C The shut-off valves on the first trailer should be closed
D All shut-off valves should be closed