40. For an ordinary four-stroke diesel engine, the exhaust valve closes _________ .
(A) after TDC (Top dead center)
(B) before TDC (Top dead center)
(C) after BDC (Bottom dead center)
(D) before BDC (Bottom dead center)

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統計： A(32), B(6), C(15), D(2), E(0) #1275882