In our daily life, some people think that smoking1help them relax. In fact, smoking is really2 Do you know that there are over 4,000 chemicals（化学药品） in cigarettes? These chemicals are 3for our bodies. They can cause cancer and 4diseases.

    The smoke from cigarettes harms not only smokers but also other people. It's5“second-hand smoke” and it can be6and has higher risks. Smokers shouldn't use smoking7them relax. They must give up smoking as soon as possible.

读中国地图，回答下列问题．

填入下面横线处的句子，与上下文衔接最恰当的一组是(    )
历史是对过去的记忆。米兰·昆德拉强调，对过去记忆的丧失，将使“人变得比大气还轻，会高高地飞起，离别大地亦即离别真实的生活。他将变得似真非真，运动自由而毫无意义”                 。
①但“知其不可而为之”
②虽然知道历史必然有大量“空白”因此有填不完的“空”
③这便是“生命中不能承受之轻”的原因所在
④而千千万万无辜的死难者，将被历史迅速遗忘，最多化为“历史教科书”上一小段无足轻重的文字或几个干瘪枯燥的数字
⑤摆脱历史记忆，生命将变得毫无意义
⑥尽量不让历史“留白”，尽可能为历史“填空”， 就更是历史学家，不，应是所有人的责任