钝角三角形ABC中，∠BAC＞90°，∠ACB=α，∠ABC=β，过点A的直线l交BC边于点D．点E在直线l上，且BC=BE．

    One day three Frenchmen who did not know English very well were talking about the English language.
The first Frenchman said, ‘I heard someone shout ‘look out’ ,I put my head out of a window and a basin of water fell on me. It seems that ‘look out’ may mean ‘don't look out!’
    The second one followed, ‘ I was once on a ship and heard the captain（船长） shout, ‘All hands on the deck(甲板)’ I put my hands on the deck and someone trod(踩)on them.’
    The third one told his friends his experience too, ‘One early morning I called on my English friend and the maid(女佣) said, ‘He is not up yet, come back in half an hour.’ When I went again for him, she said, ‘He’s not down yet.’I said, ‘If he’s not up and he is not down, where is he then?    What a strange language it is!’