Even if the shark swims away, you are not truly safe until you are out of the water. Sharks may leave temporarily and then come back to continue the attack. Get back to shore or back on the boat as quickly as possible.  If a boat is nearby, call out calmly, but loudly, for them to come to you. Stay as still as possible while waiting, as long as the shark is not actively attacking you; and get into the boat as quickly as possible, once the boat reaches you.     If you are near shore, swim quickly, but smoothly. Thrashing will attract the shark's attention again and disperse your blood, which could draw more sharks. Do the smooth reverse breast stroke, which requires less splashing than other strokes.     If you have been bitten, get treatment as soon as possible. Massive blood loss could occur, depending on where you have been bitten, so immediately take appropriate steps to stop the bleeding. Even if your wounds appear minor, it is essential to get yourself checked out. Remain calm until you get medical care, so that your blood does not pump faster through your body.

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Write a summary of the previous text in Chinese:
逃出水面。 寻求医疗救治。