A: I once heard someone shout, "Look out." I put my heard out of the window and a bucketful water fell on me. It seems that "Look out" may mean "Don't look out". B: I was once on a ship and heard the captain shout, "All hands on deck ." I put my hands on the deck and someone walked on them. C: I once called early on an English friend and the servant who came to the door said, "He's 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 neither up nor down. Where is he?" . In the dialogue the phrase "Look out" actually means "  _  ".
Don't look out Look out for the water Be careful Look everywhere