A.進(jìn)氣門關(guān)閉,排氣門關(guān)閉B.進(jìn)氣門打開(kāi),排氣門打開(kāi)C.進(jìn)氣門打開(kāi),排氣門關(guān)閉D.進(jìn)氣門關(guān)閉,排氣門打開(kāi)