A.當(dāng)接合取力器時(shí) B.當(dāng)斷開(kāi)取力器時(shí) C.當(dāng)接通聯(lián)鎖應(yīng)急開(kāi)關(guān)時(shí) D.當(dāng)切斷聯(lián)鎖應(yīng)急開(kāi)關(guān)時(shí)