材料一：治蛮夷之道，必威德兼施，使其畏感，不如此不可也。盖蛮夷非威不畏，非惠不怀，然一于威则不能感其心，一于惠则不能慑其暴，惟威惠并行，此驭蛮夷之道也。

——《明太祖实录》

材料二：新世纪新阶段的民族工作必须把各民族共同团结奋斗、共同繁荣发展作为主题。民族团结是各族人民之福，民族分裂是各族人民之祸。要倍加珍惜来之不易的民族团结大好局面，让民族团结之花开放得更加艳丽。

结合材料，分析说明我国明代民族政策与现阶段民族政策的区别，并谈谈加强民族团结的重要性。

阅读理解

    Retired nurse Sue Collins was just beginning the second length of her local pool when her morning swim suddenly became anything but a pleasure.

    Two months ago Sue, 69, who has never suffered from asthma or any other breathing problem in the past, suddenly found herself hard for breath.

    “I felt as if my throat and oesophagus (食道) were closing up,” says Sue.

    Sue is convinced the problem is related to the indoor swimming baths. “I spend half the year in Turkey and swim every day outside in a pool or the sea there and never have this problem,” she says.

    She may be right, because although a trip to the pool is the perfect exercise for many, the chlorine (氯气) used to keep the water free from germs can lead to problems.

    But in most cases it's not the chlorine that causes problems, but the by-products formed when chlorine interacts with other substances — and this is mostly due to people not showering before they enter the pool.

    “This then poisons the water for them and for others,” says Dr. Hull. “The chlorine interacts with sweat and urine(尿素) on the skin and forms by-products called chloramines that float above the surface as a gaseous solution that can be inhaled in.”

    Chloramines are heavier than air so hang over the water where they are easily breathed in. Some believe they may cause lung disorders. A Swedish study in 2013 examining the health of 146 workers at 46 indoor pools found that 17 per cent had airway trouble at work — but no problems at home.

    As Dr. Hull says: ‘People need to remember that showering isn't just for them. It is for the greater good.'

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