听力原文:M: Can't you knock on the door before you enter my office next time? W: Sorry, sir. It's just that I'm in such a hurry. Q: How does the man feel when he speaks to the woman? (17)
【单选题】In a medium speed diesel engine, a trunk type piston may be cooled by_______Ioil circulation though passages in the piston crown IIheat transfer through piston rings and liner wall