試題詳解

33.After the compression readings shown below were taken, a wet compression test was made. The second set of readings was almost the same as the first. Technician A says that a burned valve could cause these readings. Technician B says that a broken piston ring could cause these readings. Who is right？ 
(A) A only
(B) B only
(C) both A and B
(D) neither A nor B.