40. There is much scale in the jacket water cooler for main engine.

A、
A、 Much scale is found in the jacket water cooler for auxiliary engine.
;

B、
B、 Not much scale is found in the jacket water cooler for main engine.
;

C、
C、 A lot of scale is found in the jacket water cooler for main engine.
;

D、
D、 We find choked in the jacket water cooler for auxiliary engine.