任务型阅读。 阅读下面短文,请根据短文后的要求进行答题(请注意问题后的词数要求)。 [1]Swimming is one of those activities that can be learned early in life. Little children can learn to swim as soon as they walk. In fact, you need the same skills in walking as in swimming. However, believe that five is the best age to learn. By five or six, a child knows fear of water,  a very important thing to know. It's wise to be afraid, to recognize true danger. Young ones understand that the water can sometimes be very dangerous. [2]To really benefit from swimming, every swimmer should learn ____: butterfly,  backstroke,  breaststroke,  and crawl. I feel that one of these-the breaststroke-is different from the others, since some young swimmers use this stroke naturally, without any training. [3]In swimming, there are certain rules every swimmer should follow : (1) Never swim alone!  No matter how good you are in the water, don't risk drowning by swimming alone. If you swim by yourself, with no life guards or friends with you, you may get into trouble. (2) Don't go beyond your abilities. Most swimmers know enough not to swim too far from the bank or the beach Showing off by doing dangerous tricks is no good. Swim safely and you will continue to swim and alive. (3)Don't smoke. Swimming depends on a healthy body; good lungs are part of Lt. (4)Work at any activity that builds muscles. 1.What is the main idea of the passage? (no more than 10 words) ______________________________________________________ 2. Please complete the following statement with proper words. (nomore than 5 words) ________________________________ and the recognition of its danger are sensible. 3. Fill in the blank in Paragraph 2 with proper words. (no more than 7 words) _________________________________________________________________ 4.Why should not you swim alone according to the passage? ( no more than 10 words) _________________________________________________________________ 5. What does the underlined word 'it' probably refer to? (no more than 3 words) __________________________________________________________________